393 publications from this institution
Influence of Coulomb forces on Fe3O4–H2O nanofluid thermal improvement in a cavity with moving wall is examined. The final formulas are solved via Control Volume based Finite Element Method. The influences of volume fraction of Fe3O4, supplied voltage and Reynolds number on the hydrothermal characteristics are considered. Results indicate that existence of electric field can alter the nanofluid flow style. As Coulomb force augments temperature gradient along hot wall enhances. Nusselt number enhances with augment of supplied voltage.
In current article, transportation of CuO nanoparticles through a porous enclosure is demonstrated. The enclosure has complex shaped hot wall. Porous media has been simulated via two temperature equations. Magnetic force impact on nanofluid treatment was considered. Control volume based finite element method has been described to solve current article in vorticity stream function form. Single phase model was chosen for nanofluid. Nanofluid characteristics are predicted via KKL model. Roles of solid-nanofluid interface heat transfer parameter (Nhs), porosity, Hartmann and Rayleigh numbers have been illustrated. Outputs illustrated that conduction mode reduces with augment of Ra. Increasing magnetic forces make nanofluid motion to decrease. Temperature gradient of nanofluid decreases with augment of Nhs. Reducing porosity leads to enhance in Nusselt number.
No abstract is provided for this article.
Magnetic nanofluids are used in cancer therapeutics by utilizing cancer imaging and drug delivery. These are also used to kill cancerous cells without affecting the nearby healthy cells by producing higher temperatures around tumor. This investigation aims to explore the heat transfer in non-Darcy porous medium for magnetic nanofluid flowing due to external magnetic field. Nanoparticle shapes and their properties are also considered. Vorticity stream function formulation is also employed. The solutions of the resulting system of equations are found by CVFEM. Illustrations are outlined pictorially for numerous physical parameters namely, Rayleigh number, radiation parameter, Darcy number, Fe3O4-water based volume concentration and Hartmann numbers. Outcomes indicate that augmenting in Hartmann number results in reduce in velocity of nanofluid and heat transfer rate. The nanoparticle with shape Platelet gives maximum heat transfer rate.
Most of the problems in mechanical engineering include the heat transfer phenomena. Industrial engineering, cooling process, oil industry and melting, shaping and deformations, automobile industry and many other process have a heat transfer and researchers need to control it by increase/decrease devices. Fins are widely used in many industrial applications such as air conditioning, refrigeration, automobile, chemical processing equipment, and electrical chips. Also cooling by suitable fluids such as nanofluids is another application of heat transfer discussed in the present chapter, which contains following sections: 3.1 Introduction 3.2 Longitudinal Fins With Constant Profile 3.3 Natural Convection Flow of a Non-Newtonian Nanofluid 3.4. Two-Dimensional Heat Transfer in Longitudinal Rectangular and Convex Parabolic Fins 3.5 Thermal Boundary Layer on Flat Plate 3.6 Falkner–Skan Wedge Flow 3.7 Free Convection Problem
Applications of the lattice Boltzmann method (LBM) for nanofluid flow and heat transfer in the presence of a magnetic field are studied in this chapter. The basic idea of LBM and implementation of source terms and boundary conditions are presented. Then sample FORTRAN codes are presented for two important basic problems. Different methods of applying magnetohydrodynamics and nanofluid in this method are explained. After validation of present code, several examples are presented in which LBM is applied to simulate nanofluid hydrothermal behavior in the presence of a magnetic field.
No abstract is provided for this article.
Two phase nanofluid double diffusion convection in presence of induced magnetic field is analyzed. Runge-Kutta method was applied to find the solution of this problem. Numerical procedures are examined for various active parameters namely; Prandtl and Hartmann numbers, suction parameter, Buoyancy ratio, Schmidt number, thermophoretic and Brownian motion parameters. Results revealed that temperature gradient enhances with augment of suction parameter but it reduces with augment of thermophoretic parameters. Nanofluid motion reduces with augment of Schmidt and Hartmann numbers but it enhances with augment of Buoyancy ratio and thermophoretic parameters.
Effect of external magnetic source on Fe3O4- water nanofluid convection in an enclosure with sinusoidal outer cylinder is reported. Final equations are solved by means of Control Volume based Finite Element Method (CVFEM). Roles of Rayleigh number ( R a = 10 3 , 10 4 and 105), Hartmann number ( H a = 0 to 15), amplitude of the sinusoidal wall ( A = 0.1 to 0.2) and volume fraction of Fe3O4 ( ϕ = 0 and 0.04) are reported. Results show that Lorentz forces cause the thermal plume to slant to left side. Impact of adding nanoparticle is more effective in high Hartmann number. Temperature gradient near the hot wall enhances with augment of buoyancy forces but it reduces with augment of Lorentz forces.
In this article, nanofluid convective flow inside a porous enclosure is simulated by means of two-temperature model. Control volume based finite element method is employed for this purpose. Nanofluid properties are estimated by means of KKL model. Darcy- Boussinesq approximation is utilized for nanofluid flow field. Lorentz forces effects are taken into consideration. Roles of solid-nanofluid interface heat transfer parameter ( Nhs ) , Rayleigh number ( Ra ) , porosity ( ε ) , and Hartmann number ( Ha ) are examined. Outputs demonstrate that | ψ | max enhance with rise of Nhs but it augments with rise of Ra . Porosity has opposite relationship with temperature gradient.
Background It is crucial to introduce new strategies to intensify the efficiency of photovoltaic thermal (PVT) unit. The incorporation of a thermoelectric generator (TEG) within a solar unit can notably improve its electrical performance. Additionally, modifying the properties of the cooling fluid by incorporating nano-powders proves to be an effective approach in optimizing PVT systems. Methods This study delves into an inventive design for a PVT unit, exploring novel techniques to boost its performance. To enhance the cooling of the PV component, two strategies were employed: 1) the implementation of a new-style turbulator, and 2) the integration of confined jets. Thus, three cases were simulated: case 1 (without any enhancement), case 2 (with the turbulator), and case 3 (employing both techniques). Additionally, the TEG layer was incorporated with the PV layers to augment overall efficiency. The testing fluid, water, was infused with SiO2 nanoparticles, and their properties were determined using a homogeneous mixture formulation. For simulating the current 3D model, the Finite Volume Method was chosen, accounting for laminar flow in fluid zones and applying the pure conduction equation for solid zones. The impacts of altering geometry, heat flux (G), inlet velocity within the tube (Vi), and jet (Vj) on performance metrics (including PV electrical (ηPV), thermoelectric (ηTE), thermal (ηth), overall electrical (ηEl), total (ηTot)) have been detailed in the results section. Significant findings By implementing two cooling techniques, the uniformity of panel temperature experiences a notable enhancement of about 79.96 %. With an increase in the velocity of the nanofluid within the tube, there is an approximately 1.99 % improvement in the value of ηTot. Furthermore, when Vi=0.08 m/s, the values of ηEl, and ηTot see an increase of about 3.09 % and 12.59 %, respectively, upon the installation of the jet and turbulator. An augmentation in G leads to a rise in ηTot by approximately 5.32 % and 7.32 % for cases 1 and 3, respectively. When G = 810 W/m2, incorporating a jet and turbulator in the PVT system results in improvements of about 2.64 % in ηEl, and 10.45 % in ηTot. The increment of ηTot with switching from case 1 to case 3 enhances about 24.62 % with the rise of G. Moreover, as the inlet velocity of the jet increases, the values of ηTE, ηth, and ηTot enhance by about 3.43 %, 1.87 %, and 1.06 %, respectively.
Studies of fluid transport in biological organisms often concern the flow of a particular fluid inside an expanding or contracting vessel with permeable walls. For a valve, vessel exhibiting deformable boundaries, alternating wall contractions produce the effect of a physiological pump. The flow behavior inside the lymphatic exhibits a similar character. In such models, circulation is induced by successive contractions of two thin sheets, which cause the downstream convection of the sandwiched fluid. Seepage across permeable walls is clearly important to the mass transfer between blood, air, and tissue. Therefore, a substantial amount of research work has been invested in the study of the flow in different geometries in both Newtonian and non-Newtonian form. This chapter introduces differential transformation method to solve these problems, which contains the following sections: 4.1 Introduction 4.2 Two-Dimensional Viscous Flow 4.3 Magnetohydrodynamic Boundary Layer 4.4 Nanofluid Flow Over a Flat Plate 4.5 Non-Newtonian Fluid Flow Analysis
This research examines the interaction effects of an inclined magnetic field and nanofluid on forced convection heat transfer and flow irreversibility in a duct with an abrupt contraction. This contraction is created by an inclined forward facing step and is simulated using the Blocked region method. To analysis the flow irreversibility, the entropy generation number is calculated based on the second law of thermodynamics. The effects of Hartmann number H a = 0 - 100 , magnetic field inclination angle β = 0 Â ° - 90 Â ° and nanoparticles volume fraction ϕ = 0 - 0.06 on the values of friction coefficient, Nusselt number and entropy generation number are shown graphically. The results present that the Hartmann number and inclination angle of the magnetic field have the reverse effects on the heat transfer rate, whiles their influences on the flow irreversibility is significantly increasing. Also, total entropy generation number and average Nusselt number increase as the volume fraction of nanoparticles enhances from 0 to 0.06.
In this study, heat and mass transfer characteristic of unsteady nanofluid flow between parallel plates is investigated. The important effect of Brownian motion and thermophoresis has been included in the model of nanofluid. The governing equations are solved via Differential Transformation Method. The validity of this method was verified by comparison previous work which is done for viscous fluid. The analytical investigation is carried out for different governing parameters namely; the squeeze number, Hartmann number, Schmidt number, Brownian motion parameter, thermophoretic parameter and Eckert number. The results indicate that skin friction coefficient has direct relationship with Hartmann number and squeeze number. Also it can be found that Nusselt number increases with increase of Hartmann number, Eckert number and Schmidt number but it is decreases with augment of squeeze number.
Ferrofluid convective heat transfer in a cavity with sinusoidal cold wall is examined under the influence of external magnetic source. The working fluid is Fe3O4-water nanofluid. Single phase model is used to estimate the behavior of nanofluid. Vorticity stream function formulation is utilized to eliminate pressure gradient source terms. New numerical method is chosen namely Control volume base finite element method. Influences of Rayleigh, Hartmann numbers, amplitude of the sinusoidal wall and volume fraction of Fe3O4 on hydrothermal characteristics are presented. Results indicate that temperature gradient enhances as space between cold and hot walls reduces at low buoyancy force. Lorentz forces cause the nanofluid velocity to reduce and augment the thermal boundary layer thickness. Nusselt number augments with rise of buoyancy forces but it decreases with augment of Lorentz forces.
In this study effect of magnetic field dependent (MFD) viscosity on free convection heat transfer of nanofluid in an enclosure is investigated. The bottom wall has constant flux heating element. Single phase nanofluid model is utilized considering Brownian motion. Control Volume based Finite Element Method is applied to simulate this problem. The effects of viscosity parameter, Hartmann number and Rayleigh number on hydrothermal behavior have been examined. Results show that Nusselt number is an increasing function of Rayleigh number and volume fraction of nanoparticle while it is a decreasing function of viscosity parameter and Hartmann number. Also it can be found that reduction of Nusselt number due to MFD viscosity effect are more sensible for high Rayleigh number and low Hartmann number.
Performance enhancement of Latent Heat Thermal Energy Storage Systems (LHTESS) containing Phase Change Material (PCM) during discharging process has been discussed in present study. Storage and retrieval of thermal energy in LHTESS occur during solid-liquid phase change. This system is used to establish balance between energy supply and demand, but the main restriction for this system is the weakness of thermal conductivity of PCM. Several enhancement techniques are employed in order to overcome this problem. In the present study, the method of nanoparticles dispersion in the pure PCM to make Nano-Enhanced Phase Change Material (NEPCM) and adding fins with innovative structure are applied to expedite solidification process. The abovementioned techniques are analyzed separately. First the effect of geometry parameters of the fin on the system performance is investigated and after that, Response Surface Method optimization is employed in order to find the best fin array. Then the effect of volume fraction on solidification rate is studied and comparison between nanoparticle dispersion and adding fin is carried out. The numerical approach in this paper is Standard Galerkin Finite Element Method. In this work, the innovative fin configuration is inspired from snowflake crystal structure and the efficiency of nanoparticles dispersion in PCM and adding fin with different structures on LHTESS performance have been examined from the viewpoint of either discharging expedition or maximum energy storage capacity, which are proposed as the novelties here. Results indicate that employing fin of any structure, is a more efficient enhancement technique for discharging process of LHTESS in comparison with nanoparticle dispersion from the viewpoint of both maximum energy storage capacity and solidification rate. Also it is found that immersing optimized Snowflake shaped fin into the PCM enhances significantly the solidification rate in comparison with LHTESS with common fin arrays.
Hydrothermal behavior in a water-to-air double-pipe heat exchanger is studied experimentally and numerically. To achieve fully developed conditions, the heat exchanger was built with additional lengths before and after the test section. Commercial code (ANSYS 14) is used for numerical section. In order to enhance rate of heat transfer, discontinuous helical fins is utilized. Results show that Nusselt number augments with the enhancement of Reynolds number and Prandtl number, which are calculated at bulk temperature. The use of square section helical fins also shows a higher heat transfer enhancement rate than that of the circular one. Thermal performance factor is an increasing function of the open area ratio.
In this research, Fe3O4–water nanofluid flow in a permeable medium under the influence of external magnetic source is simulated. Effect of nanoparticle's shape on thermal conductivity is taken into consideration. CVFEM is employed to solve the final equations which are obtained with vorticity stream function formulation. Figures are depicted for various values of Darcy number ( D a ) , radiation parameter ( R d ) , Fe3O4–water volume fraction (ϕ), Rayleigh ( R a ) and Hartmann ( H a ) numbers. Results demonstrate that Greatest Nusselt number obtains for Platelet shaped Fe3O4 nanoparticle. Increasing in Hartmann number results in decreasing in velocity of nanofluid and Nusselt number.
