Begell House Inc.
Heat Transfer Research
HTR
1064-2285
49
8
2018
THREE-DIMENSIONAL NATURAL CONVECTION AND ENTROPY GENERATION IN TALL RECTANGULAR ENCLOSURES FILLED WITH STRATIFIED NANOFLUID/AIR FLUIDS
685-702
Mahmoud
Salari
Department of Mechanical Engineering, Imam Hossein University, Tehran, Iran
Abbas
Kasaeipoor
Department of Mechanical Engineering, Imam Hossein University, Tehran, Iran
Emad Hasani
Malekshah
Faculty of Engineering, Department of Mechanical Engineering, University of Isfahan, Hezar Jerib
Avenue, Isfahan 81746-73441, Iran; Department of Mechanical Engineering, Imam Hossein University, Tehran, Iran
Fluid flow, heat transfer, and volumetric entropy generation due to the three-dimensional natural convection within a tall rectangular enclosure filled with two immiscible/stratified fluids have been studied comprehensively as a simplified thermal model for each cell of lead–acid batteries. The stratified fluids consist of an MWCNT–SiO2 (15%–85%)/EG nanofluid at the bottom and air in the top region of the enclosure. The Navier–Stokes equations are solved based on a three-dimensional form, and finite volume approach is utilized. The boundary condition for the interface involve heat and mass transfer and shear stress. The heated side walls have a constant heat flux, the bottom and top parts of the side walls have a symmetry condition showing the existence of similar fluid flow in the neighbor cell. The top and bottom walls are cooled by environment
temperature. The three-dimensional flow structure and temperature field are obtained and analyzed at mid-depth
in a two-dimensional form. Different operating parameters such as the aspect ratio (12 < AR < 120), Rayleigh number
(103 < Ra < 106), and the solid volume fraction (φ = 0.005–0.02) are considered with fluid flow, heat transfer, and volumetric entropy generation. The results show that the dominant heat transfer mechanism is conduction at the tall enclosures with a high aspect ratio. Moreover, the interface between the nanofluid and air phases is acting like an insulation medium banning the heat energy to escape from the nanofluid region to the top cold wall. The Nusselt number enhances with increasing Rayleigh number and solid volume fraction. Higher volumetric entropy generation occurs at higher Rayleigh number and lower aspect ratio and solid volume fraction.
PARTICLE SWARM OPTIMIZATION WITH LÉVY FLIGHTS FOR HEAT SOURCE ESTIMATION
703-717
Obed
Cortés-Aburto
Departamento de Ingeniería Mecatrónica, Universidad Politécnica de Puebla, Juan C. Bonilla, Puebla, México
José-Alfredo
Hernández-Pérez
Centro de Investigación en Ingeniería y Ciencias Aplicadas, Universidad Autónoma del Estado de
Morelos, Cuernavaca, Morelos, México
Rafael
Rojas-Rodríguez
Departamento de Ingeniería Mecatrónica, Universidad Politécnica de Puebla, Juan C. Bonilla, Puebla, México
Rita-Marina
Aceves-Pérez
Departamento de Ingeniería Mecatrónica, Universidad Politécnica de Puebla, Juan C. Bonilla, Puebla, México
Salvador-Antonio
Arroyo-Díaz
Departamento de Ingeniería Mecatrónica, Universidad Politécnica de Puebla, Juan C. Bonilla, Puebla, México
José-Víctor
Galaviz-Rodríguez
Universidad Tecnológica de Tlaxcala, Huamantla, Tlaxcala, México
In this work, a new approach, Lévy flight Particle Swarm Optimization, is applied to estimate the solution of an inverse heat transfer problem. Results show a good performance of this scheme. Compared with standard Particle Swarm Optimization, it exhibits better precision (from 3 to 5 parameters) and less running time (average of 24.90%).
NUMERICAL INVESTIGATION OF NATURAL-CONVECTION HEAT TRANSFER CHARACTERISTICS OF Al2O3-WATER NANOFLUID FLOW THROUGH POROUS MEDIA EMBEDDED IN A SQUARE CAVITY
719-745
Siva Sai
Vadri
Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036, India
K. Arul
Prakash
Fluid Mechanics Laboratory Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai 600036, India
Arvind
Pattamatta
Department of Mechanical Engineering, Indian Institute of Technology Madras,
Chennai–600036, India
In this study, natural-convection heat transfer characteristics of Al2O3-water nanofluid flow through a homogeneous porous medium embedded in a square cavity with several pairs of heaters and coolers located inside are investigated numerically. The two-dimensional equations governing the nanofluid flow and heat transfer through the porous medium are discretized using Streamline Upwind Petrov-Galerkin (SUPG) based Finite Element Method (FEM). The generalized Darcy-Brinkman-Forchheimer's porous medium model is used in this analysis. The average Nusselt number in the cases of the base fluid without a porous medium, of a nanofluid without a porous medium, and a nanofluid with a porous medium are compared for different Rayleigh numbers. It is found that in the case of the nanofluid with a porous medium the highest value of average Nusselt number was obtained. In addition to this, the effect of the Darcy number and the porosity on the pattern of streamlines and isotherms is investigated. It is also observed that the average Nusselt number increases with increasing Darcy number and decreases with increasing porosity and nanoparticle volume fraction.
ENTROPY GENERATION IN BLOOD FLOW WITH HEAT AND MASS TRANSFER FOR THE ELLIS FLUID MODEL
747-760
Muhammad Mubashir
Bhatti
College of Mathematics and Systems Science, Shandong University of Science and Technology,
Qingdao, Shandong, 266590, China; Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072,
China
M. Ali
Abbas
Department of Mathematics, Shanghai University, Shanghai 200444, China; Department of Computer Science, Karakoram International University, Skardu Campus, Gilgit Baltistan 16100, Pakistan
M. M.
Rashidi
Department of Civil Engineering, University of Birmingham, Edjbaston B15 2TT, Birmingham; Shanghai Key Lab of Vehicle Aerodynamics and Vehicle Thermal Management Systems, Tongji
University, Shanghai 201804, China
In this paper, entropy generation during heat and mass transfer in peristaltic Ellis fluid (blood) flow through a nonuniform channel is investigated. The walls of the channel are considered to be compliant. The governing equations for the Ellis fluid model, as well as the energy, concentration, and entropy equations are simplified using the approximation
of long wavelength (0 << λ → ∞) and creeping flow regime (Re → 0). The solution for the resulting differential equations is obtained analytically, and closed form solutions are presented. Mathematical and graphical analyses of the velocity profile, temperature profile, concentration profile, and entropy profile are presented for the Schmidt, Eckert, Soret, Prandtl, and Brinkmann numbers, compliant wall parameters, and Ellis fluid parameters. It is observed that the fluid parameters provide a significant resistance to the velocity of the fluid.Moreover, the Eckert and Schmidt numbers show opposite impact on the concentration profile as compared to temperature distribution. The present investigation is also applicable in treatment of various diagnostic problems and different drug delivery systems in pharmacological, thermal, and biomedical engineering.
NANOPARTICLE VOLUME FRACTION OPTIMIZATION FOR EFFICIENT HEAT TRANSFER AND HEAT FLOW PROBLEMS IN A NANOFLUID
761-771
Sarkhosh Seddighi
Chaharborj
School of Mathematics and Statistics, Carleton University, Ottawa, K1S 5B6, Canada; Department of Mathematics, Islamic Azad University, Bushehr Branch, Bushehr, Iran
Abbas
Moameni
School of Mathematics and Statistics, Carleton University, Ottawa, K1S 5B6, Canada
The main purpose of this paper is optimization of the nanoparticle volume fraction in a boundary layer flow, beneath a uniform free stream permeable continuous moving surface in a nanofluid. First, a theoretical relation between the nanoparticle volume fraction and the velocity profile has been obtained. Then the optimization of the volume fraction for the Ag, Cu, and CuO nanoparticles is studied. Finally, a combination of several nanoparticles is considered and the corresponding optimization problem is analyzed. As it turns out, one can use a right combination of several nanoparticles to ensure a more efficient heat transfer with a lower operational cost.
ON THE ONSET OF NATURAL CONVECTION IN A PARTIALLY COOLED CYLINDER
773-786
Jose
Nuñez
Escuela Nacional de Estudios Superiores, Unidad Morelia, Universidad Nacional Autónoma de
México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex Hacienda de San José de la Huerta,
58190, Morelia, Michoacán, México
Alberto
Beltrán
Instituto de Investigaciones en Materiales, Unidad Morelia, Universidad Nacional Autónoma
de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex Hacienda de San José de la
Huerta, C.P. 58190, Morelia, Michoacán, México
Recent experimental configurations like the liquid metal electrode for the development of a liquid metal battery and the inverted Bridgman configuration for growing crystals involve natural convection of fluids confined in vertical cylinders heated from below and partially cooled from above. A cylindrical cavity subjected to such conditions is studied from a numerical point of view, assuming the Rayleigh number, the noncooled size, and the aspect ratio (height/diameter) parameters over ranges 103 ≤ Ra ≤ 105, 0 ≤ γ ≤ 0.875, and 0.5 ≤ α ≤ 1.25, respectively, for all cases with Pr = 6.67 being assumed. The governing equations for natural convection are discretized employing a mixed Fourier–Finite volume method using the SIMPLEC algorithm as velocity decoupling strategy. Steady flow transitions from axisymmetric to nonaxisymmetric were obtained; interestingly, the average Nusselt number shows a monotonic de-creasing behavior as a function of while an increasing behavior as function of Ra is observed. In particular, symmetry breaking instability as a function of critical parameters of the convective flow is determined by a numerical stability analysis. Finally, a stability map for Ra vs. γ is constructed for α = 1.0.