scholarly journals Enhanced heat transfer in H2O inspired by Al2O3 and γAl2O3 nanomaterials and effective nanofluid models

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110236
Author(s):  
Adnan ◽  
Umar Khan ◽  
Naveed Ahmed ◽  
Syed Tauseef Mohyud-Din
Keyword(s):  
Heat Transfer ◽  
Colloidal Suspension ◽  
Fluid Motion ◽  
Flow Characteristics ◽  
Heat Transfer Analysis ◽  
Flow Parameters ◽  
Thermal Improvement ◽  
Infinite Region ◽  
Layer Region ◽  
Performance Rate

Currently, thermal improvement in the nanofluids over a curved Riga sheet is a topic of interest and attained popularity among the researchers. Therefore, the colloidal suspension of water suspended by [Formula: see text] and [Formula: see text] over a curved Riga surface is modeled for the heat transfer analysis. The nondimensionalization of the model is accomplished via invertible variables. On the basis of dynamic viscosities and thermal conductivities of [Formula: see text] and [Formula: see text] nanoparticles, two nanofluid models developed over a semi-infinite region. Then, the models solved numerically and found graphical results for the flow characteristics, thermophysical properties and local thermal performance rate by altering the pertinent flow parameters. It is examined that the fluid motion rapidly decreases for [Formula: see text] and momentum boundary layer region decreases. The squeezed and curvature parameters lead to reduce in the nanofluid velocity. The temperature of more magnetized enhances significantly. Thermophysical characteristics of the nanofluids enhance for higher volumetric fraction factor. More heat transfer at the Riga surface for higher M and R.

scholarly journals Heat Transfer Analysis for Viscous Fluid Flow with the Newtonian Heating and Effect of Magnetic Force in a Rotating Regime

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Rashid Ayub ◽  
Shahzad Ahmad ◽  
Muhammad Imran Asjad ◽  
Mushtaq Ahmad
Keyword(s):  
Viscous Fluid ◽  
Fluid Motion ◽  
Velocity Fields ◽  
Heat Transfer Analysis ◽  
Convection Flow ◽  
Newtonian Heating ◽  
Flow Parameters ◽  
Laplace Transform Technique ◽  
The Laplace Transform ◽  
Temperature And Velocity Fields

In this article, an unsteady free convection flow of MHD viscous fluid over a vertical rotating plate with Newtonian heating and heat generation is analyzed. The dimensionless governing equations for temperature and velocity fields are solved using the Laplace transform technique. Analytical solutions are obtained for the temperature and components of velocity fields. The obtained solutions satisfy the initial and boundary conditions. Some physical aspects of flow parameters on the fluid motion are presented graphically.

Fluid flow analysis of cilia beating in a curved channel in the presence of magnetic field and heat transfer

2020 ◽  
Vol 98 (2) ◽  
pp. 191-197 ◽  
Author(s):  
Hina Sadaf ◽  
S. Nadeem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Velocity Profile ◽  
Flow Analysis ◽  
Fluid Motion ◽  
Flow Characteristics ◽  
Physical Parameters ◽  
Curved Channel ◽  
Radial Magnetic Field ◽  
Fluid Flow Analysis

This paper investigates fluid motion generated by cilia and a pressure gradient in a curved channel. The flow analysis is carried out in the presence of heat transfer and radial magnetic field. The leading equations are simplified under the familiar suppositions of large wavelength and small Reynolds number approximations. An exact solution has been developed for the velocity profile. The flow characteristics of the viscous fluid are computed in the presence of cilia and metachronal wave velocity. The effects of several stimulating parameters on the flow and heat transfer are studied in detail through graphs. It is found that symmetry of the velocity profile is broken owing to bending of the channel. The radially varying magnetic field decreases the velocity field, but near the left ciliated wall it induces the opposite behavior. It is also found that velocity profile increases due to increase in buoyancy forces throughout the domain. Numerical consequences for velocity profile are also accessible in the table for diverse values of the physical parameters.

Heat transfer augmentation in a radial curved microchannel

2021 ◽  
pp. 095440892110412
Author(s):  
Nitin Kumar Mamidi ◽  
Karthik Balasubramanian ◽  
Kiran Kumar Kupireddi ◽  
V P Chandramohan ◽  
Poh Seng Lee ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Characteristics ◽  
Heat Removal ◽  
Heat Transfer Analysis ◽  
Cooling Systems ◽  
Number Range ◽  
Cooling Performance ◽  
Curvature Ratio ◽  
Reynolds Number Range

Rapid advancement toward miniaturization has emerged with confront for superior heat dissipation techniques. Of all the available cooling systems, microchannel-based cooling systems stand out to provide better cooling performance through superior heat removal abilities. In the present study, the cooling performance and hydraulic flow characteristics of a radial curved microchannel with three curvature ratios were numerically investigated and compared with a radial straight microchannel. Unlike the conventional straight microchannels, curved channels possess better fluid mixing as a result of the centrifugal force caused due to curvature. This phenomenon has a significant effect on heat transfer and fluid flow characteristics. Work on radial curved microchannels has been scarce and there is a lot of potential to augment the heat transfer with lower pumping power particularly with a central inlet. A three-dimensional conjugate heat transfer analysis was carried out for three radial curved microchannels and a radial straight microchannel using the ANSYS Fluent commercial software with the Reynolds number range of 125–275. The results showed a Nusselt number increment of 36.38% for radial curved microchannels when compared to the radial straight microchannel. Further, the lowest average wall temperature was noted for the radial curved microchannel with a curvature ratio of 0.17 which was 15.63 °C lower when compared to that in a radial straight microchannel for the same Reynolds number. Contours of velocity and temperature are presented at various locations along the stream to aid the results. The overall performance of all three radial curved microchannels was found to be higher than that of the radial straight microchannel in the Reynolds number range considered, out of which the maximum performance factor of 1.245 was obtained for the radial curved microchannel with a curvature ratio of 0.17 as compared to the radial straight microchannel.

A Heat-Transfer Analysis of the Solidification of a Binary Eutectic System

1967 ◽  
Vol 89 (3) ◽  
pp. 230-233 ◽  
Author(s):  
R. H. Tien ◽  
G. E. Geiger
Keyword(s):  
Heat Transfer ◽  
Error Function ◽  
Pure Metal ◽  
Point Of View ◽  
Heat Transfer Analysis ◽  
Graphical Form ◽  
Eutectic System ◽  
Function Solution ◽  
Infinite Region ◽  
Binary Eutectic

The solidification of a binary system differs from a pure metal in that the latent heat effect no longer occurs at the melting point but rather in a freezing zone between the liquidus and solidus temperatures. Such solidification is analyzed from a heat-transfer point of view. The system considered occupies a semi-infinite region, is initially at the liquidus temperature, and at all subsequent times the surface temperature is considered constant; the fraction solid is assumed to be linear with distance within the freezing zone between the solidus and liquidus. The heat released during solidification is treated as a discontinuous heat generation. This corresponds to the nonequilibrium freezing of a eutectic system. The temperature distribution and thickness of each region are calculated as a function of time using the error function solution and the heat-balance integral; the results are given in graphical form.

Heat Transfer in a Radially Rotating Four-Pass Serpentine Channel With Staggered Half-V Rib Turbulators

2000 ◽  
Vol 123 (1) ◽  
pp. 39-50 ◽  
Author(s):  
G. J. Hwang ◽  
S. C. Tzeng ◽  
C. P. Mao ◽  
C. Y. Soong
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Enhancement ◽  
Serpentine Channel ◽  
Ribbed Channel ◽  
Flow Parameters ◽  
Rib Turbulators ◽  
Rib Arrangement

The present work is concerned with experimental investigation of the convective heat transfer in a radially rotating four-pass serpentine channel. Two types of staggered half-V rib turbulators are considered to examine their effects on heat transfer enhancement. The coolant air is pressurized and pre-cooled to compensate for the low rotating rate and low temperature or density difference in key parameters of thermal and flow characteristics. The geometric dimensions are fixed, whereas the ranges of the thermal and flow parameters in the present measurements are 20,000⩽Re⩽40,000,0⩽Ro⩽0.21, and Gr/Re2∼O10−2. The present results disclose the effects of the pressurized flow, rib arrangement, channel rotation, and centrifugal buoyancy on the local heat transfer in each passage of the channel. Finally, the present data are fitted on correlation equations for evaluation of local heat transfer in the rotating four-pass ribbed channel configurations considered.

Effect of thickness and thermal conductivity of metal foams filled in a vertical channel – a numerical study

2019 ◽  
Vol 29 (1) ◽  
pp. 184-203 ◽  
Author(s):  
Banjara Kotresha ◽  
N. Gnanasekaran
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Metal Foam ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Vertical Channel ◽  
Metal Foams ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Content Type

PurposeThis paper aims to discuss about the two-dimensional numerical simulations of fluid flow and heat transfer through high thermal conductivity metal foams filled in a vertical channel using the commercial software ANSYS FLUENT.Design/methodology/approachThe Darcy Extended Forchheirmer model is considered for the metal foam region to evaluate the flow characteristics and the local thermal non-equilibrium heat transfer model is considered for the heat transfer analysis; thus the resulting problem becomes conjugate heat transfer.FindingsResults obtained based on the present simulations are validated with the experimental results available in literature and the agreement was found to be good. Parametric studies reveal that the Nusselt number increases in the presence of porous medium with increasing thickness but the effect because of the change in thermal conductivity was found to be insignificant. The results of heat transfer for the metal foams filled in the vertical channel are compared with the clear channel in terms of Colburn j factor and performance factor.Practical implicationsThis paper serves as the current relevance in electronic cooling so as to open up more parametric and optimization studies to develop new class of materials for the enhancement of heat transfer.Originality/valueThe novelty of the present study is to quantify the effect of metal foam thermal conductivity and thickness on the performance of heat transfer and hydrodynamics of the vertical channel for an inlet velocity range of 0.03-3 m/s.

An Experimental Study of Detailed Flow and Heat Transfer Analysis in a Single Row Narrow Impingement Channel

2014 ◽  
Author(s):  
Jahed Hossain ◽  
Lucky V. Tran ◽  
Jayanta S. Kapat ◽  
Erik Fernandez ◽  
Rajan Kumar
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Turbulence Models ◽  
Heat Transfer Analysis ◽  
Temperature Sensitive ◽  
Single Row ◽  
Flow Physics ◽  
Flow And Heat Transfer ◽  
Target Wall

An experimental investigation of detailed flow and heat transfer in a narrow impingement channel was studied; the channel included 15 inline jets in a single row with a jet-to-target wall distance of 3 jet diameters. The spanwise length of the channel was 4 jet diameters, and a streamwise jet spacing of 5 jet diameters was considered for the current study. Both the flow physics and heat transfer tests were run at an average jet Reynolds number of 30,000. Temperature sensitive paint was used to study heat transfer at the target wall. Along with other parameters, jet-to-jet interaction in a narrow row impingement channel plays a significant role on heat transfer distribution at the side and target walls as the self-induced jet cross flow tends to bend the downstream jets. The present work shows detailed information of flow physics using Particle Image Velocimetry (PIV). PIV measurements were taken at planes normal to the target wall along the jet centerline for several jets. The flow field and heat transfer data was compared between the experiment and CFD in order to understand the relationship between flow characteristics and heat transfer. The experimental data gathered from PIV can be used as benchmark data for validating the current state of the art RANS turbulence models as well as for Large Eddy Simulation (LES).

scholarly journals Effect of magnetic field on fluid flow characteristics and augmentation of heat transfer in a heat exchanger

2021 ◽  
Author(s):  
Mohammed Almeshaal ◽  
◽  
Sujoy Saha ◽  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Exchanger ◽  
Control Volume ◽  
Flow Characteristics ◽  
Research Area ◽  
Flow Parameters ◽  
Fluid Flow Characteristics ◽  
The Impact

The study of fluid flow, subjected to an external magnetic field has become an attractive and demanding research area because of its huge applications. In this work, water base magnetic nanofluid dynamics, taking into account the Magnetohydrodynamics (MHD) phenomenon has been explicitly investigated. In this study, governing equations are coupled with Magnetohydrodynamics (MHD) and are solved with the help of a finite volume procedure based on a control volume approach. The numerical outcomes of the simulation are depicted and discussed sequentially in terms of different contour and flow parameters. The impact of Magnetic number arising from Magneto Hydro Dynamics (MHD) ranging from 302 to 377 for a fixed Reynolds number of 100 on the flow characteristics has been presented in detail. The flow parameters like wall shear and pressure of wall are increased with increasing Magnetic number and the number of recirculating bubbles increases with decreasing in Magnetic number. Thus, to generate the maximum number of recirculating bubbles,a lower magnetic number is being recommended. The formation of the recirculating zone increases the retention time of fluid which results in the enhancement of heat transfer for a specific surface of a heat exchanger.

Rectangular-Plate Turbulator Effects on Heat Transfer and Near-Wall Flow Characteristics in Fan Flows

2004 ◽  
Vol 20 (1) ◽  
pp. 33-41 ◽  
Author(s):  
T.Y. Chen ◽  
Y.H. Chen
Keyword(s):  
Heat Transfer ◽  
Rectangular Plate ◽  
Flow Characteristics ◽  
Fluid Flows ◽  
Mean Velocity ◽  
Heat Transfer Augmentation ◽  
Flow Parameters ◽  
Wall Flow ◽  
Aluminum Plates ◽  
Near Wall

ABSTRACTHeat transfer and near-wall flow characteristics in an inherently swirling fan flow, containing rectangular-plate turbulators with 45° and 90° angles of attack, were experimentally investigated. The heat transfer characteristics for uniform flows with the turbulators were also investigated for comparison. Eight heated aluminum plates, installed along a bottom duct-wall, were used as the heat transfer surfaces, which allows the studies of heat transfer variations along the duct and the studies of the relations between the local fluid flows and heat transfer variations. Three-component mean and fluctuating velocities were measured using a laser Doppler velocimetry to obtain the near-wall flow parameters, including the axial mean velocity, axial vorticity and turbulent kinetic energy. The temperatures on the eight heat transfer surfaces were measured using thermocouples to obtain the Stanton number distributions. Results suggest that the rectangular-plate turbulators in fan flows may cause the increases in the near-wall flow parameters and, consequently, augment the heat transfer, especially around the flow reattachment regions. Also, the rectangular-plate turbulator effect on heat transfer augmentation in fan flows may be as attractive as that in uniform flows at the investigated X/H ranges.

scholarly journals CONSTRUCTAL DESIGN APPLIED TO A FINNED CHANNEL UNDER FORCED CONVECTION FLOWS WITH DIFFERENT IMPOSED PRESSURE DROPS

2017 ◽  
Vol 16 (2) ◽  
pp. 72
Author(s):  
B. C. Feijo ◽  
F. B. Teixeira ◽  
M. S. Pereira ◽  
L. A. O. Rocha ◽  
J. N. V. Goulart ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Degrees Of Freedom ◽  
Fluid Motion ◽  
Convection Heat Transfer ◽  
Lower Surface ◽  
Pressure Drops ◽  
Constructal Design ◽  
Inlet Stream ◽  
Thermal Improvement ◽  
The Difference

This paper aims to numerically study the heat transfer in a two dimensional finned channel under laminar, incompressible and forced convective flow with adiabatic walls. The main purpose is to maximize the convection heat transfer by changing the fin’s dimensions by means of Constructal Design. Numerical computations are performed for different Bejan numbers ranging from 0.182 up to 18.2. For all simulations the Prandlt number is kept constant, Pr = 0.71. The fluid motion throughout the channel is caused by imposition of pressure difference between inlet/outlet surfaces. Concerning heat transfer, it is caused by the difference of temperature between the inlet stream of fluid and the heated fins placed at the channel surfaces. The first fin is positioned in the lower surface of the channel while the second one is placed in the upper one. The problem is submitted to three constraints, the channel area (H × L), area of two fins and occupancy areas for the fins. It is considered here that both fins have the same fraction area (ratio between the fins and occupancy areas) f = 0.2. The problem is submitted to three degrees of freedom: H/L (ratio between height and length of channel), H3/L3 and H4/L4 which represent the ratio between the height and length of the first and second fin, respectively. Here, the second fin remains unchanged, being its dimensions H4/L4 = 2.0, whereas the first one is free to modify its dimensions, H3/L3. The channel dimensions are also constant. The solutions are sought using the conservation equations of mass, momentum and energy being these ones discretized through the Finite Volume Method (FVM). Results showed the importance of Constructal Design application for thermal improvement of the problem. Thermal efficiency differences of 5 times where achieved when comparing the best and worst cases. Other important observation is concerned with the effect of ratio H3/L3 over heat transfer ratio (q) which varied significantly from a case where a pressure drop is imposed in the channel to other case where the driven force is caused by imposition of velocity field at the channel inlet.

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