Natural Convection Mass Transfer Research Articles

Convection heat and mass transfer of non-Newtonian fluids in porous media with Soret and Dufour effects using a two-sided space fractional derivative model

Non-Newtonian fluids within heterogeneous porous media may give rise to complex spatial energy and mass distributions owing to non-local mechanisms, the modeling of which remains unclear. This study investigates the natural convection heat and mass transfer of non-Newtonian fluids in porous media, considering the Soret and Dufour effects. A strongly coupled model is developed to quantify the coupled transport of energy and reactive pollutants with the non-Newtonian fluid. The constitutive equation for the non-Newtonian fluid is described by a two-sided Caputo type space fractional velocity gradient. The governing equation, with a symmetric diffusion term, is effectively solved using a stable and convergent shifted Grünwald–Letnikov formula. The influences of three important parameters, which are the average skin friction coefficient, the average Nusselt number, and the Sherwood number, on fluid heat and mass transfer are calculated and analyzed. Numerical results reveal a significant interaction between the fractional derivative and the buoyancy ratio number, both of which affect the average skin friction coefficient. Furthermore, the average Nusselt number increases with the Dufour number while decreasing with the average Sherwood number. These findings enhance our understandings of the dynamics of energy and mass co-transport in non-Newtonian fluids, particularly in relation to their constitutive equation featuring spatial non-local properties.

Enhanced Efficiency of MHD-Driven Double-Diffusive Natural Convection in Ternary Hybrid Nanofluid-Filled Quadrantal Enclosure: A Numerical Study

The study investigates the performance of fluid flow, thermal, and mass transport within a cavity, highlighting its application in various engineering sectors like nuclear reactors and solar collectors. Currently, the focus is on enhancing heat and mass transfer through the use of ternary hybrid nanofluid. Motivated by this, our research delves into the efficiency of double-diffusive natural convective (DDNC) flow, heat, and mass transfer of a ternary hybrid nanosuspension (a mixture of Cu-CuO-Al2O3 in water) in a quadrantal enclosure. The enclosure’s lower wall is set to high temperatures and concentrations (Th and Ch), while the vertical wall is kept at lower levels (Tc and Cc). The curved wall is thermally insulated, with no temperature or concentration gradients. We utilize the finite element method, a distinguished numerical approach, to solve the dimensionless partial differential equations governing the system. Our analysis examines the effects of nanoparticle volume fraction, Rayleigh number, Hartmann number, and Lewis number on flow and thermal patterns, assessed through Nusselt and Sherwood numbers using streamlines, isotherms, isoconcentration, and other appropriate representations. The results show that ternary hybrid nanofluid outperforms both nanofluid and hybrid nanofluid, exhibiting a more substantial enhancement in heat transfer efficiency with increasing volume concentration of nanoparticles.

Condensation heat transfer between a vertical superhydrophobic aluminum surface and moist air under natural convection

Condensation heat transfer at superhydrophobic surfaces has raised a lot of interest due to their potential application in atmospheric water harvesting and air-conditioning. In moist air, the condensation heat transfer using a superhydrophobic surface can be negatively affected by the existence of a large amount of non-condensable gas, namely, the dry air. Besides, the air flow pattern would substantially affect the surface condensation rate due to the convective mass transfer of water vapor. In this study, the condensation regime of a superhydrophobic aluminum surface vertically positioned in quiescent moist air was visualized and the condensation rate was experimentally investigated. Condensation experiments were also performed by using hydrophobic, hydrophilic, and superhydrophilic surfaces for comparison. The condensation rate of the superhydrophobic surface was consistent with that of other surfaces, though the condensation regimes of the four surfaces were quite different. The average deviation between the experimental condensation rate and the empirical correlation of natural convection heat and mass transfer was within 12%. The result indicates that vapor transfer induced by diffusion and convection in the boundary layer rather than the heat transfer resistance associated with condensate dominates the condensation heat and mass transfer between the moist air and the superhydrophobic surface.

THREE TEMPERATURE MODEL FOR HEAT AND MASS TRANSFER IN NON-NEWTONIAN Cu-EG NANOFLUIDS EMBEDDED WITH PERMEABLE MEDIUM

In the current study, the impacts of local thermal non-equilibrium model and Cu-EG Oldroyd-B nanofluid layer on natural convective heat and mass transfer in a permeable medium are investigated. The transport equations are framed using modified Buongiorno two-phase Darcy model with different temperature profiles for fluid, particle, and porous-matrix phases. The thermophysical properties of the considered nanofluid are calculated using available experimental data. In the current situation, weak, non-linear analysis has been performed to find the Nusselt number and Sherwood number by solving finite amplitude equations using NDSolve in Mathematica 12.0. Influence of different parameters including viscoelastic parameters, LTNE parameters, thermal Rayleigh number, and nanoparticle volume fraction on heat and mass transfer mechanisms are explained graphically. An increase in the Nusselt number with the rising values of volume fraction of nanoparticles is registered and reach its maximum value at φ = 0.05 due to enhanced thermal conductivity. The significant findings for Oldroyd-B nanofluids are that the stress relaxation parameter declines heat transfer while strain retardation parameter promotes it. This study improves the theoretical understanding of heat transfer in porous media and facilitates the use of such theoretical models in practical applications.

MHD natural convection heat and mass transfer flow over an inclined porous plate with thermophoresis and nonlinear thermal radiation effects

AbstractThis study examined magnetohydrodynamic natural convection mass and heat transfer flow of an electrically conducting and viscous incompressible fluid over an inclined porous plate with thermophoresis, suction/injection, and uniform magnetic field. The mathematical model governing the fluid behavior surrounding an inclined plate is solved through the Runge–Kutta–Fehlberg fourth–fifth order after utilizing the shooting method. The implication of active dimensionless parameters in the governing equations is fully discussed in detail. The results obtained show that, in the existence of nonlinear thermal radiation and suction/injection, the heat transfer rises with the increase in the angle of inclination but it decreases with the mass transfer and plate shear stress. Furthermore, the heat transfer rate experiences a serious setback due to the increase in the buoyancy force but improves the plate shear stress. The mass transfer is directly proportional to the thermophoresis effect. In addition, Particle suction increases the velocity and temperature curves while it declines the concentration profile, but the opposite is valid for injection. Nonlinear thermal radiation positively affects the temperature, velocity, and concentration profiles. The Lorentz force suppresses the fluid transport and retard the rate of particle concentration, but promotes the fluid temperature distribution. It is also deduced that increasing the rate of particle suction from 0 to 1, accounts for over 76% increase in the particle deposition at the plate surface. However, increasing the rate of particle injection from 0.004 to 0.250 accounts for an over 83% decrease in the particle deposition at the plate surface.

Hall and Rotation Effects on Radiating and Reacting MHD Flow past an Accelerated Permeable Plate with Soret and Dufour Effects

This article investigates numerically the effects of Hall current and rotation effects on radiating and chemically reacting unsteady MHD natural convection flow past an accelerated infinite vertical permeable plate in the presence of Soret and Dufour effects. The dimensionless coupled non-linear governing partial differential equations of the problem are solved numerically by employing finite element method. The influence of various physical parameters influencing the flow on the primary velocity, secondary velocity, temperature and the species concentration are displayed graphically whilst the numerical results of the primary skin friction, secondary skin-friction, Nusselt number and the Sherwood number are presented in tabular form. Results reveals that magnetic parameter, radiation parameter and chemical reaction rate tends to depreciate both primary and secondary velocity components whilst Hall, Soret and Dufour effects have reverse trend. Rotation parameter tends to retard fluid flow in the primary flow direction and accelerate fluid flow in the secondary flow direction. Thermal boundary layer thickness decreases with increasing radiation parameter whilst the reverse trend is noticed with increasing Dufour effect. Thermal diffusion effect causes to improve concentration boundary layer thickness whilst chemical reaction rate has reverse impact. These parameters have similar effect on the primary and secondary skin-frictions whilst opposite effect was noticed on the Nusselt and Sherwood numbers. This model problem finds an important in engineering and industrial application such as MHD generators, food processing, heat exchangers devices and internal rotation rate of the sun.
 HIGHLIGHTS
 
 The problem investigate the effects of Hall current and rotation effects on radiating and reacting on unsteady magnetohydrodynamics (MHD) natural convection heat and mass transfer flow over an infinite vertical porous plate embedded in a uniform porous medium taking Soret and Dufour effects into account
 The resulting partial differential equations governing the fluid flow are solved numerically using the finite element method. In order to determine the effects of various pertinent parameters and to investigate the important flow features, the numerical calculations for fluid velocity, temperature and species concentration are computed and shown graphically whereas skin friction, Nusselt number and Sherwood number at the plate are evaluated and depicted in tabular form
 The model problem finds an important in engineering and industrial application
 
 GRAPHICAL ABSTRACT

Heat and mass transfer analysis of natural convection in a liquid desiccant closed-loop system: The effect of heat source and heat sink temperature

Considering the importance of providing healthy and suitable indoor air condition efficiently, liquid desiccant air condition systems are the focus of study in recent years. The concept of natural convection heat and mass transfer loop is introduced. The system is a closed-loop consisting of two three-fluid hollow fiber membrane heat and mass transfer exchangers played as absorber and regenerator. The system was run under standard conditions with an inlet air flow rate of 6 m3/h. The sensitivity analysis was made to reveal the effect of heat source and heat sink temperature on the system performance. The heat sink and heat source temperature lie between 15–25 °C and 50–70 °C respectively and the outlet air temperature and humidity ratio, moisture removal rate, cooling capacity and coefficient of performance are the evaluating indexes. The results show that despite the convectional desiccant loops the high solution flow rate is not desirable and instead the concentration gradient in the loop is the most important factor. For each heat source temperature, there is an interval of heat sink temperature for which the solution flow rate is the maximum and the concentration gradient is the minimum. Under operating conditions of the present study, the maximum obtained COP is 0.71 which is for temperature pair of (55 °C, 20 °C).

Numerical investigation of chemical reaction, Soret and Dufour impacts on MHD free convective gyrating flow through a vertical porous channel

The extensive variety of issues include reactions kinetics, simulations and optimizations of different models of reactors including basic explorations of the processes of temperature, mass and momentum transfer that taken places with chemical reaction. Based on this criteria, it is discussed the impacts of the Soret and Dufour consequences on natural convective heat and mass transfer for the unsteady two dimensional boundary layer flow through a vertical channel/duct with the influence of viscous dissipation, invariable suction into the description. The governing dimensionless partial differential equations are solved digitally making use of the implicit Crank-Nicolson method. The velocity, temperature, and concentration dispensations are addressed computationally and demonstrated by the graphs. Numerical quantities of the skin-friction, Nusselt number and Sherwood number at the plate are found for a choice of assessments of substantial parameters and which are displayed by tabular manner. It is significant to notice that, Soret impacts emerge in suspended mixture of particles and fluids. These phenomenons are reasoned with the temperature gradients; hence, the movements of fluid molecules in the hottest zone and highest energy level in this region transfer the particles towards the coldest region. It is also most useful in chemical engineering.

Hall and ion‐slip effects on MHD natural convective flow past an unbounded vertical porous channel with thermodiffusion

AbstractThe consequences of Soret in addition to Dufour of natural convection heat and mass transfer for the unsteady three‐dimensional boundary layer flow through a perpendicular condition of the existence of viscous dissipation, invariable suction, Hall as well as ion slip consequences into relation. The prevailing partial differential equation is dissolved digitally utilizing the implicit Crank–Nicolson finite difference method. The velocity, temperature, as well as concentration dispensations, is addressed computationally and demonstrated by the graphs. Numerical values of the Nusselt number, skin friction as well as Sherwoods numbers nearby the plate are discussed for a choice of values of substantial parameters and are displayed in a tabular manner. It is noticed that the temperature of the fluid diminishes with higher Prandtl numbers. The resulting velocity diminishes with the growing Hartmann number. Rotation, Soret, and Dufour parameters strengthen the velocity and momentum boundary layer thickness. The velocity intensifies through growing Hall and ion‐slip parameters and the revoke trend is acquired with enhancement in suction parameter.

Nonlinear approximation for natural convection and mass transfer in a vertical channel

AbstractThis paper presents a nonlinear approximation for natural convection magnetohydrodynamics flow and mass transfer in a vertical passage filled with nanofluid with an induced magnetic field effect. The influence of the thermophoretic and Brownian motion diffusion is taken into account. The mathematical formulation comprises the significant impact of nonlinear density variation with temperature and concentration (NDTC) in the momentum equation. The uniform magnetic field is considered to be perpendicular to the vertical channel. The wall at y = 0 is considered to be nonconducting at constant heat flux whereas electrically conducting at a constant temperature at y = h. The analytic solution is achieved via the perturbation method for small thermophoretic and Brownian motion diffusion effects. The implications of the embedded parameters on the flow properties are demonstrated through graphs and tables. During the analysis, we discovered that under the influence of thermophoretic and Brownian motion diffusion, suction parameter augment decreases the mass transfer rate but the converse is true for Schmidt number. NDTC in the buoyancy term enhances the skin friction. The skin friction could be reduced by increasing the numerical values of Hartmann number, Prandtl number, magnetic Prandtl number, and suction parameter.

Influence of nanoparticle shapes on natural convection flow with heat and mass transfer rates of nanofluids with fractional derivative

Nanofluids are gaining extensive attention due to their thermo‐physical properties in technological and industrial fields for controlling the effects of heat transfer. Classical nanofluid studies are generally confined to models described by partial differential equations of an integer order where the memory effect and hereditary properties of materials are neglected. In order to overcome these downsides, the present work focuses on studying nanofluids with fractional derivative formed by differential equations with Caputo time derivatives that provides memory effect on nanofluid characteristics. Also, investigation on natural convective flow, heat, and mass transfer of nanofluids formed by different base fluids with different shapes of copper nanoparticles past an infinite vertical plate with radiation effect is carried out. The governing fractional differential equations are solved by employing Laplace transform technique with suitable boundary conditions. The different base fluids—water (H2O), SA:sodium alginate (C6H9Na O7), and EG:ethylene glycol (C2H6O2) and different shapes of nanoparticles—blade, brick, platelet, and cylinder are considered for the study. The exact solutions are obtained for the temperature, concentration, and velocity distributions and the respective Nusselt number, Sherwood number, and skin‐friction coefficient. The influence of non‐dimensional parameters provides physical interpretations of temperature, concentration, and velocity fields, Nusselt number, Sherwood number, and skin friction in detail with the help of graphical representations. From the results, it is found that nanofluid with water‐based blade‐shaped nanoparticle exhibits more velocity and temperature distributions. Also, strengthen of fluid flow, temperature, and concentration of nanofluids are inversely correlate with fractional order derivatives.

Natural convection mass transfer correlation of the electropolishing of horizontal cylinders with active ends

ABSTRACT To contribute to quantifying the process of electropolishing, the rates of electropolishing of a horizontal cylinder with active ends were studied under natural convection by measuring the limiting current of the anodic dissolution of copper cylinders in H3PO4. Cylinder diameters and H3PO4 concentrations were changed to provide a wide range of Sc⋅Gr (Schmidt and Grashof numbers). The data for a horizontal cylinder with active ends for the conditions < Sc < , 6.5 × 108 < Sc⋅Gr > were correlated by the equation . For hollow horizontal cylinders (pipes) the outer surface data fit the equation . Comparison of the equations obtained for a horizontal cylinder with the equations obtained by previous studies on vertical cylinders with active ends revealed that the orientation of the workpiece plays an important role in determining the rate of electropolishing.

Limit of the buoyancy ratio in Boussinesq approximation for double-diffusive convection in binary mixture

This paper deals with a mathematical and numerical investigation of double-diffusive natural convective heat and mass transfer in a cavity filled with Newtonian fluid with significant density and mass diffusivity changes. In such a situation, the assumption of the Boussinesq approximation is not justified, and an appropriate model based on a set of Low Mach Number equations is used. The active parts of two vertical walls of the cavity are maintained at fixed but different temperatures and concentrations, while the other two walls, as well as inactive areas of the sidewalls, are considered to be adiabatic and impermeable to mass transfer. The coupled momentum, energy, and solute transfer equations in binary mixtures of ideal gases are solved through a global iterative procedure based on the finite volume methods in the context of the low Mach number approximation. The study includes the effect of the buoyancy ratio N with the aim to find its application limit in the Boussinesq conditions. The results show that if we use the Boussinesq approximation to study double-diffusive convection, the value of parameter N must be between −6 and 27.

SORET AND MEMORY EFFECTS ON UNSTEADY MHD NATURAL CONVECTION HEAT AND MASS TRANSFER FLOW IN A POROUS MEDIUM WITH NEWTONIAN HEATING

SORET AND MEMORY EFFECTS ON UNSTEADY MHD NATURAL CONVECTION HEAT AND MASS TRANSFER FLOW IN A POROUS MEDIUM WITH NEWTONIAN HEATING

Soret and Dufour Effects on Unsteady Free Convection Fluid Flow in the Presence of Hall Current and Heat Flux

Unsteady MHD natural convective heat and mass transfer flow through a semi-infinite vertical porous plate in a rotating system have been investigated with the combined Soret and Dufour effects in the presence of Hall current and constant heat flux. It is considered that the porous plate is subjected to constant heat flux. The obtained non-dimensional, non-similar coupled non-linear and partial differential equations have been solved by explicit finite difference technique. Numerical solutions for velocities, temperature and concentration distributions are obtained for various parameters by the above mentioned technique. The local and average shear stresses, Nusselt number as well as Sherwood number are also investigated. The stability conditions and convergence criteria of the explicit finite difference scheme are established for finding the restriction of the values of various parameters to get more accuracy. The obtained results are illustrated with the help of graphs to observe the effects of various legitimate parameters.

Heat and Mass Transfer in an Inclined Bi-L-Shaped Layered Porous Media: Effect of Buoyancy Ration

The effect of buoyancy ratio on the two dimensional natural convection heat and mass transfer generated in an inclined square bi-L-shaped layered porous cavity filled with Newtonian fluid has been investigated numerically. Each porous layer is considered isotropic, homogeneous and saturated with the same fluid. The cavity is heated and salted from below where as the vertical walls are assumed to be adiabatic and impermeable. The physical model for the momentum conservation equation makes use of the Darcy-Brinkman-Forcheimer model, and the set of coupled equations is solved using a finite volume approach. The power-law scheme is used to evaluate the flow, heat and mass fluxes across each of the control volume boundaries. Tri diagonal matrix algorithm with under-relaxation is used in conjunction with iterations to solve the nonlinear discretized equations. An in-house code developed for this study is validated using previous studies. The results are presented graphically in terms of streamlines, isotherms and iso-concentrations. In addition, the heat and mass transfer rate in the cavity is measured in terms of the average Nusselt and Sherwood numbers.

Non-Darcian effect on double-diffusive natural convection inside aninclined square Dupuit-Darcy porous cavity under a magnetic field

This paper presents a numerical study of a double diffusive convection in an inclined square porous cavity filled with an electrically conducting binary mixture. The upper and bottom walls are maintained at a constant temperatures and concentrations whereas the left and right walls are assumed to be adiabatic and impermeable. A uniform and tilted magnetic field is applied at an angle, ?, about the horizontal, it is obvious that this is related to the orientation of the magnetic force that can help or oppose the buoyant force. The Dupuit-Darcy flow model, which includes effects of the inertial parameter, with the Boussinesq approximation, energy, and species transport equations are solved numerically using the classical finite difference method. Governing parameters of the problem under study are the thermal Rayleigh number, Hartmann number, Lewis number, the buoyancy ratio, inclination angle, and tilting angle of the magnetic field. The numerical results are reported on the contours of streamline, temperature, and concentration and for the average Nusselt and Sherwood numbers for various parametric conditions. It is demonstrated that both the inertial effect parameter and the magnetic field, have a strong influence on the strength of the natural convection heat and mass transfer within the porous layer.

Effects of soret, dufour, hall current and rotation on MHD natural convective heat and mass transfer flow past an accelerated vertical plate through a porous medium

This article concentrates on the impact of Hall current, Radiation, Soret, and Dufour on an unsteady MHD Natural convective flow over an infinite vertical plate fixed in a porous media. The entire system is supposed to revolve with an unvarying angular velocity Ω′around the perpendicular to the plate and an unvarying transverse magnetic field is enforced along the normal to the plate which is coordinated in the fluid area. The solution of the non-deimensional governing equations along with the boundary conditions are solved by using effeicient Galerkin Method. The effect of different pertinent flow parameters on velocity, temperature, and concentration distributions and the numerical outcomes are examined and revealed graphically. With the increase of Sorent number the concentration profile increases and reverse trend is observed in the case of Dufour numbers. Comparision done with the recent work on exceptional instances of the problem is acquired and is seen to be in accord.

Steady natural convection heat and mass transfer flow through a vertical porous channel with variable viscosity and thermal conductivity

AbstractThe present article studies the effects of suction/injection and variable physical properties on steady natural convection flow through a vertical channel. The investigation was done analytically using Differential Transformation Method (DTM). The variability in viscosity and thermal conductivity are considered linear function of temperature. The governing equations are transformed into a set of coupled nonlinear ordinary differential equations. Results obtained were compared with exact solution when some of the flow conditions were relaxed and results from DTM show an excellent agreement with the exact solution which was obtained analytically. The influence of the flow parameters on fluid temperature, concentration, and velocity are presented graphically and discussed for variations of the governing parameters. From the course of investigation, it was found that an increase in suction (S &gt; 0) through the heated plate causes fluid temperature, velocity as well as concentration to decrease. However, an increase in injection causes heat transfer rate as well as skin friction at the heated plate to decrease.

Thermal Radiation and Variable Pressure Effects on Natural Convective Heat and Mass Transfer Fluid Flow in Porous Medium

The study investigates the interaction of free convective flow with thermal radiation and variable pressure on natural convective heat and mass transfer fluid flow in porous medium. Solutions for time dependent energy, concentration and momentum equations were obtained by the perturbation series method after transforming into ordinary differential equations. The effect of various flow parameters such as: suction/injection ( δ) radiation (R ) magnetic field (M ) heat source (S ) chemical reaction ( Rc) on the skin friction, rate of heat transfer, velocity, temperature, and concentration profile influencing the physical situation were discussed with the aid of line graphs.&#x0D; Keywords: Thermal Radiation, Variable pressure, Perturbation, Natural Convection