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M M Rashidi - One of the best experts on this subject based on the ideXlab platform.
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study of nanofluid forced Convection Heat Transfer in a bent channel by means of lattice boltzmann method
Physics of Fluids, 2018Co-Authors: Rasul Mohebbi, M M Rashidi, Zhigang YangAbstract:In this paper, the laminar forced Convection Heat Transfer of nanofluid through a bent channel was numerically investigated. The lattice Boltzmann method was used for solving the governing equations in the domain. The effect of different parameters such as Reynolds number (50 ≤ Re ≤ 150), vertical passage ratio (2.0 ≤ M ≤ 4.0), and nanoparticle solid volume fractions (Φ = 0, 0.01, 0.03, 0.05) are analyzed in terms of streamlines, isotherms, and local Nusselt numbers. It was concluded from this study that the local and average Nusselt number increased with increasing nanoparticle volume fraction regardless of Re and M. Moreover, the effect of the nanofluid concentration on the increment of Heat Transfer was more remarkable at higher values of the Reynolds number. Simulations show that by increasing the Reynolds number or decreasing the vertical passage ratio, the local and average Nusselt number increases.
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numerical simulation of natural Convection Heat Transfer of a nanofluid in an l shaped enclosure with a Heating obstacle
Journal of The Taiwan Institute of Chemical Engineers, 2017Co-Authors: Rasul Mohebbi, M M RashidiAbstract:Abstract The natural Convection Heat Transfer in an L -shaped enclosure being filled with Al 2 O 3 /water nanofluid and having an internal Heating obstacle is presented in this paper by LBM. The combination of the three topics (L-shaped cavity, hot obstacle and nanofluid) is the main novelty of the present study. The statistics focused specifically on the effects of different key parameters same as Ra number (10 3 –10 6 ), aspect ratio of the channel (0.2–0.6), nano-particle volume fraction of (0–0.05), position and height of the hot obstacle and nanoparticle diameter (20–80 nm) on the Heat Transfer inside the L -shaped enclosure. The average Nusselt numbers were also calculated for the obstacle sides. The obtained results showed that the streamlines and isotherm lines had different patterns at different Ra numbers, aspect ratio and the height of obstacle. The Heat Transfer phenomena were highly affected by the Heating obstacle position. With the nanofluid and the reducing AR, the increasing Ra number, the decreasing nanoparticle diameter and the increasing height of the obstacle, an increase in the Heat Transfer and the individual Nusselt number appeared. Moreover, the maximum Nusselt number was observed when the Heating obstacle was located in the lower position inside the left wall.
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numerical investigation of water alumina nanofluid natural Convection Heat Transfer and entropy generation in a baffled l shaped cavity
Journal of Molecular Liquids, 2016Co-Authors: T Armaghani, Abbas Kasaeipoor, N Alavi, M M RashidiAbstract:Abstract This article presents a numerical study of natural Convection Heat Transfer and entropy generation of water-alumina nanofluid in baffled L-shaped cavity. The left vertical and bottom walls are placed in hot and constant Th temperature and the middle horizontal and right vertical walls are in cold and constant Tc temperature. The other walls are insulated. The baffle's temperature is Tc and their existence in cavity has a lot of impacts on flow behavior and it could disrupt flow order. The governing equations are solved numerically with Finite Volume Method using the SIMPLER algorithm simultaneously. The Convection Heat Transfer results show: AR (aspect ratio) increasing enhances Heat Transfer. With dimensional ratio increasing, nanofluid has a greater impact on Nusselt growing. By baffle length increasing nanofluid has less impact on cooling cavity, as a result Heat Transfer raises. The entropy generation of mentioned parameters are also investigated and discussed. Finally, with studding the e = Sm/Num (named thermal performance) the best AR and baffle length are introduced.
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numerical investigation of magnetic field effect on mixed Convection Heat Transfer of nanofluid in a channel with sinusoidal walls
Journal of Magnetism and Magnetic Materials, 2016Co-Authors: M M Rashidi, Mohammad Nasiri, Marzieh Khezerloo, Najib LaraqiAbstract:Abstract In this study, mixed Convection Heat Transfer of nano-fluid flow in vertical channel with sinusoidal walls under magnetic field effect is investigated numerically. The Heat Transfer and hydrodynamic characteristics have been examined. This study has performed for 500≤Re≤1000, 5×104≤Gr≤1×106 , three amplitude sine wave (0.1, 0.2 and 0.3) and three values of Hartman numbers (0, 5 and 10). Water was utilized as the base fluid and Al2O3 is the considered nano-particle. Flow is assumed two dimensional, laminar, steady and incompressible. As well the thermo-physical properties of nano-fluid are considered constant. The Boussinesq approximation used for calculated the density variations. The average Nusslet number increases by increasing the Grashof number for nano-fluids with different volume fraction. The average Nusselt and Poiseuille number increase as Reynolds number increases. Also, the average Nusselt number and Poiseuille number increases by increasing the Hartman number.
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forced Convection Heat Transfer in a semi annulus under the influence of a variable magnetic field
International Journal of Heat and Mass Transfer, 2016Co-Authors: M Sheikholeslami, M M Rashidi, K VajraveluAbstract:Abstract Since advective transport in a ferrofluid can be controlled by using an external magnetic field, magnetic nanofluid (ferrofluid) has various applications to Heat Transfer processes. Unlike free or forced Convection, Ferrohydrodynamic Convection is not yet well described. In the literature we see papers with constant magnetic fields; but the assumptions are not accurate, since the fields do not comply with the Maxwell’s equations of electromagnetism. In this study, forced Convection Heat Transfer in a semi annulus lid under the influence of a variable magnetic field is studied. The enclosure is filled with ferrofluid (Fe3O4–water). Control Volume based Finite Element Method (CVFEM) is used to solve the governing equations considering both Ferrohydrodynamic (FHD) and Magnetohydrodynamic (MHD) effects. It is assumed that the magnetization of the fluid is varying linearly with temperature and magnetic field intensity. The effects Reynolds number, nanoparticle volume fraction parameter, magnetic number arising from FHD, and Hartmann number arising from MHD are analyzed. Obtained results indicate that the effects of Kelvin forces are more pronounced for high Reynolds number. Heat Transfer enhancement has direct relationship with the Reynolds number and the magnetic number; while it has inverse relationship with the Hartmann number.
M Sheikholeslami - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of nanofluid forced Convection Heat Transfer improvement in existence of magnetic field using lattice boltzmann method
International Journal of Heat and Mass Transfer, 2017Co-Authors: M Sheikholeslami, Tasawar Hayat, A AlsaediAbstract:In this paper, nanofluid forced Convection Heat Transfer is investigated in existence of magnetic field. Three dimensional simulations are presented by means of Lattice Boltzmann Method. Koo-Kleinstreuer-Li (KKL) model is considered to estimate the properties of nanofluid. Roles of Hartmann number, Reynolds number, Al2O3 volume fraction are illustrated graphically. Outputs are depicted in forms of velocity, isokinetic energy, streamlines, isotherms contours and Nusselt number. Results demonstrate that velocity of nanofluid augments with rise of Reynolds number and Al2O3 volume fraction but it reduces with increase of Hartmann number. Convection mode reduces with enhance of Lorentz forces. Temperature gradient over the moving wall augments with augment of hot surface velocity and Al2O3 volume fraction.
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electrohydrodynamic free Convection Heat Transfer of a nanofluid in a semi annulus enclosure with a sinusoidal wall
Numerical Heat Transfer Part A-applications, 2016Co-Authors: M Sheikholeslami, Ali J ChamkhaAbstract:ABSTRACTNatural Convection Heat Transfer of a nanofluid in the presence of an electric field is investigated. The control volume finite element method (CVFEM) is utilized to simulate this problem. A Fe3O4–ethylene glycol nanofluid is used as the working fluid. The effect of the electric field on nanofluid viscosity is taken into account. Numerical investigation is conducted for several values of Rayleigh number, nanoparticle volume fraction, and the voltage supplied. The numerical results show that the voltage used can change the flow shape. The Coulomb force causes the isotherms to become denser near the bottom wall. Heat Transfer rises with increase in the voltage supplied and Rayleigh number. The effect of electric field on Heat Transfer is more pronounced at low Rayleigh numbers due to the predomination of the conduction mechanism.
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forced Convection Heat Transfer in a semi annulus under the influence of a variable magnetic field
International Journal of Heat and Mass Transfer, 2016Co-Authors: M Sheikholeslami, M M Rashidi, K VajraveluAbstract:Abstract Since advective transport in a ferrofluid can be controlled by using an external magnetic field, magnetic nanofluid (ferrofluid) has various applications to Heat Transfer processes. Unlike free or forced Convection, Ferrohydrodynamic Convection is not yet well described. In the literature we see papers with constant magnetic fields; but the assumptions are not accurate, since the fields do not comply with the Maxwell’s equations of electromagnetism. In this study, forced Convection Heat Transfer in a semi annulus lid under the influence of a variable magnetic field is studied. The enclosure is filled with ferrofluid (Fe3O4–water). Control Volume based Finite Element Method (CVFEM) is used to solve the governing equations considering both Ferrohydrodynamic (FHD) and Magnetohydrodynamic (MHD) effects. It is assumed that the magnetization of the fluid is varying linearly with temperature and magnetic field intensity. The effects Reynolds number, nanoparticle volume fraction parameter, magnetic number arising from FHD, and Hartmann number arising from MHD are analyzed. Obtained results indicate that the effects of Kelvin forces are more pronounced for high Reynolds number. Heat Transfer enhancement has direct relationship with the Reynolds number and the magnetic number; while it has inverse relationship with the Hartmann number.
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effect of non uniform magnetic field on forced Convection Heat Transfer of fe3o4 water nanofluid
Computer Methods in Applied Mechanics and Engineering, 2015Co-Authors: M Sheikholeslami, M M Rashidi, D. D. GanjiAbstract:In this paper force Convection Heat Transfer in a lid driven semi annulus enclosure is studied in presence of non-uniform magnetic field. The enclosure is filled with Fe3O4–water nanofluid. It is assumed that the magnetization of the fluid is varying linearly with temperature and magnetic field intensity. Control volume based finite element method is used to solve the governing equations in the form of vorticity–stream function formulation. The calculations were performed for different governing parameters namely, the Reynolds number, nanoparticle volume fraction and Hartmann number. Results show that Nusselt number has direct relationship with Reynolds number, nanoparticle volume fraction while it has reverse relationship with Hartmann number.
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lattice boltzmann simulation of magnetohydrodynamic natural Convection Heat Transfer of al2o3 water nanofluid in a horizontal cylindrical enclosure with an inner triangular cylinder
International Journal of Heat and Mass Transfer, 2015Co-Authors: M Sheikholeslami, M Gorjibandpy, K VajraveluAbstract:Abstract In this study the lattice Boltzmann method is applied to investigate the effect of magnetic field on natural Convection Heat Transfer of Al2O3–water nanofluid in a two-dimensional horizontal annulus. In this model, the effect of Brownian motion on the effective thermal conductivity is also considered. The effective thermal conductivity and the effective viscosity of nanofluid are calculated by KKL (Koo–Kleinstreuer–Li) correlation. The effect of nanoparticle volume fraction for the enhancement of Heat Transfer was examined for several sets of values of Rayleigh and Hartmann numbers. Also, a correlation of the Nusselt number with physical parameters is presented. The obtained results indicate that the value of the maximum stream function decreases with increasing Hartmann number. Furthermore, we notice that the Nusselt number has a direct relationship with the Rayleigh number; but quite the opposite is true with the Hartmann number. The obtained results indicate that the Lattice Boltzmann method with double-population is a powerful approach for the simulation of natural Convection Heat Transfer in nanofluids in regions with curved boundaries.
Sanjay K. Roy - One of the best experts on this subject based on the ideXlab platform.
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Laminar forced Convection Heat Transfer with phase change material suspensions
International Communications In Heat And Mass Transfer, 2001Co-Authors: Sanjay K. Roy, Branko L. AvanicAbstract:This paper presents results related to laminar forced Convection Heat Transfer to a phase change material suspension in a circular duct with constant wall Heat flux. An effective specific Heat approach has been used to model the Heat Transfer process for a flow with a fully developed velocity profile. The model has been verified by comparing its numerical predictions with previous theoritical results as well as experimental data. A simple correlation for wall temperature rise as a function of the tube length that can be used for future design has been developed based on a parametric study. ?? 2001 Elsevier Science Ltd.
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Laminar forced Convection Heat Transfer with phase change material emulsions
International Communications in Heat and Mass Transfer, 1997Co-Authors: Sanjay K. Roy, Branko L. AvanicAbstract:Results of an experimental study of laminar forced Convection Heat Transfer in a circular duct with a phase change material emulsion (n-octadecane in water) are presented in this paper. The bulk Stefan numbers considered in this study range up to 3.0 and the concentration of phase change material range up to 30% by volume. The results show that the Heat Transfer characteristics for phase change material emulsions are similar to those of microencapsulated phase change material suspensions, thus confirming that the microcapsule walls do not affect the Heat Transfer process significantly.
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Natural Convection Heat Transfer from a vertical flat plate with phase change material suspensions
Journal of Enhanced Heat Transfer, 1996Co-Authors: M Harhira, Sanjay K. Roy, S. SenguptaAbstract:A numerical model has been developed for laminar natural Convection Heat Transfer from an isothermal vertical flat plate with a phase change material suspension as the Heat Transfer medium. Results show that the use of phase change material suspensions can increase the Nusselt number by as much as 8 times compared to a single phase fluid. The dominant parameters affecting the Heat Transfer are found to be the Prandtl number, the Rayleigh number, the volumetric concentration of the phase change material, the plate length to particle radius ratio and the bulk Stefan number. Other parameters, the particle to fluid thermal conductivity ratio, the Archimedes number, the Schmidt number and the buoyancy ratio do not have a significant effect on the Heat Transfer.
Branko L. Avanic - One of the best experts on this subject based on the ideXlab platform.
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Laminar forced Convection Heat Transfer with phase change material suspensions
International Communications In Heat And Mass Transfer, 2001Co-Authors: Sanjay K. Roy, Branko L. AvanicAbstract:This paper presents results related to laminar forced Convection Heat Transfer to a phase change material suspension in a circular duct with constant wall Heat flux. An effective specific Heat approach has been used to model the Heat Transfer process for a flow with a fully developed velocity profile. The model has been verified by comparing its numerical predictions with previous theoritical results as well as experimental data. A simple correlation for wall temperature rise as a function of the tube length that can be used for future design has been developed based on a parametric study. ?? 2001 Elsevier Science Ltd.
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Laminar forced Convection Heat Transfer with phase change material emulsions
International Communications in Heat and Mass Transfer, 1997Co-Authors: Sanjay K. Roy, Branko L. AvanicAbstract:Results of an experimental study of laminar forced Convection Heat Transfer in a circular duct with a phase change material emulsion (n-octadecane in water) are presented in this paper. The bulk Stefan numbers considered in this study range up to 3.0 and the concentration of phase change material range up to 30% by volume. The results show that the Heat Transfer characteristics for phase change material emulsions are similar to those of microencapsulated phase change material suspensions, thus confirming that the microcapsule walls do not affect the Heat Transfer process significantly.
Peixue Jiang - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical investigation of Convection Heat Transfer of co2 at supercritical pressures in a vertical mini tube
International Journal of Heat and Mass Transfer, 2008Co-Authors: Peixue Jiang, Yu ZhangAbstract:Abstract Convection Heat Transfer of CO 2 at supercritical pressures in a 0.27 mm diameter vertical mini-tube was investigated experimentally and numerically for inlet Reynolds numbers exceeding 4.0 × 10 3 . The tests investigated the effects of Heat flux, flow direction, buoyancy and flow acceleration on the Convection Heat Transfer. The experimental results indicate that the flow direction, buoyancy and flow acceleration have little influence on the local wall temperature, with no deterioration of the Convection Heat Transfer observed in either flow direction for the studied conditions. The Heat Transfer coefficient initially increases with increasing Heat flux and then decreases with further increases in the Heat flux for both upward and downward flows. These phenomena are due to the variation of the thermophysical properties, especially c p . The numerical results correspond well with the experimental data using several turbulence models, especially the Realizable k – e turbulence model.
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a computational study of Convection Heat Transfer to co2 at supercritical pressures in a vertical mini tube
International Journal of Thermal Sciences, 2005Co-Authors: S He, Peixue Jiang, Yijun Xu, J D JacksonAbstract:Abstract Computational simulations of experiments on turbulent Convection Heat Transfer of carbon dioxide at supercritical pressures in a vertical tube of diameter 0.948 mm have been carried out using low-Reynolds number eddy viscosity turbulence models. The simulations were able to reproduce the general features exhibited in the experiments, although, in some cases, the details between the simulations and the experiments were very different. A better understanding of the problem has been developed based on the information generated by the simulations on the detailed flow and turbulence fields. It has been shown that for mini tubes such as the one used in the current study, the buoyancy effect is generally insignificant. However, Heat Transfer can still be significantly impaired as a result of flow acceleration when the Heating is strong, which causes a reduction in turbulence production. Such an effect can be described in terms of the Heating acceleration parameter Ω 1 . This parameter correlates reasonably well the data from all the cases considered in the current study.
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experimental research on Convection Heat Transfer in sintered porous plate channels
International Journal of Heat and Mass Transfer, 2004Co-Authors: Peixue Jiang, Meng Li, T J Lu, Lei YuAbstract:Abstract Forced Convection Heat Transfer of water and air in sintered porous plate channels was investigated experimentally. The effects of fluid velocity, particle diameter, type of porous media (sintered or non-sintered), and fluid properties on the Convection Heat Transfer and Heat Transfer enhancement were investigated. The results showed that the Convection Heat Transfer in the sintered porous plate channel was more intense than in the non-sintered porous plate channel due to the reduced thermal contact resistance and the reduced porosity near the wall in the sintered material, especially for Convection Heat Transfer of air. For the tested conditions, the local Heat Transfer coefficients in the sintered porous plate channels were increased up to 15 times for water and 30 times for air. The Heat Transfer enhancement due to the sintered porous media with air intensified sharply with increasing flow rate. However, the influence of particle diameter on the Convection Heat Transfer in the sintered porous media was not great. The effective thermal conductivity of the sintered porous media was found to be much higher than for non-sintered porous media due to the improved thermal contact caused by the sintering process.
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a computational study of Convection Heat Transfer to co2 at supercritical pressures in a vertical mini tube
ASME 2004 2nd International Conference on Microchannels and Minichannels, 2004Co-Authors: S He, Peixue Jiang, Yijun Xu, J D JacksonAbstract:Computational simulations of experiments on turbulent Convection Heat Transfer of carbon dioxide at supercritical pressures in a vertical tube of diameter 0.948 mm have been carried out using low-Reynolds number eddy viscosity turbulence models. The simulations were able to reproduce the general features exhibited in the experiments. The modelling study has provided valuable information on the detailed flow and turbulence fields. It has been shown that for mini tubes such as the one used in the current study, the buoyancy effect is generally insignificant. Heat Transfer can be significantly impaired when the Heating is strong. This is due to the reduced turbulence production, induced by the flow acceleration which is in turn caused by strong Heating.Copyright © 2004 by ASME
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Forced Convection Heat Transfer in plate channels filled with packed beds or sintered porous media
Tsinghua Science and Technology, 2002Co-Authors: Peixue Jiang, Meng LiAbstract:In the present work, forced Convection Heat Transfer in plate channels filled with metallic or non-metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non-equilibrium model. The numerical simulation results are compared with experimental data. The difference between Convection Heat Transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of Convection Heat Transfer of air or water in packed beds using the local thermal non-equilibrium model and the variable porosity model agrees well with the experimental data. The Convection Heat Transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of Convection Heat Transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.