Numerical Study of Natural Convective Heat Transfer in a Two-Dimensional Cavity With Centrally Located Partition Utilizing Nanofluids

2009 ◽  
Vol 1 (3) ◽  
Author(s):  
S. H. Anilkumar ◽  
Biju T. Kuzhiveli
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Finite Difference Schemes ◽  
Valuable Insight ◽  
Computational Domain ◽  
Two Dimensional ◽  
Volume Fractions ◽  
Aspect Ratios ◽  
Wide Range

A two-dimensional single-phase natural convective heat transfer in a cavity with centrally located thin partition utilizing nanofluids has been numerically analyzed. The nanofluid used, which is composed of aluminum nanoparticles in suspension of Benzene, was provided at various solid volume fractions. The study is carried out numerically for a range of Rayleigh numbers, solid volume fractions, partition heights, and aspect ratios. Regions with the same velocity and temperature distributions are identified as a symmetry of sections. One-half of such a rectangular region is chosen as the computational domain, taking into account the symmetry about the thin partition. The governing equations are modeled by a stream function-vorticity formulation and are solved numerically by finite-difference schemes. Comparison with previously published numerical and experimental results showed excellent agreement. It is demonstrated that the partition height has a strong effect on both the heat transfer rate and the flow pattern. Results are presented in the form of streamlines and isotherm plots. The variation in the local Nusselt number along the thin partition provides valuable insight into the physical processes. A new correlation is proposed for the heat transfer studies in a wide range of thermal and geometric parameters.

The Effect of Thermal Wall Properties on Natural Convection in Inclined Rectangular Cells

1982 ◽  
Vol 104 (1) ◽  
pp. 111-117 ◽  
Author(s):  
B. A. Meyer ◽  
J. W. Mitchell ◽  
M. M. El-Wakil
Keyword(s):  
Heat Transfer ◽  
Cell Wall ◽  
Natural Convection ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Conductive Heat ◽  
Numerical Work ◽  
Aspect Ratios ◽  
Convection Problem ◽  
Natural Convection Problem

The effects of cell wall thickness and thermal conductivity on natural convective heat transfer within inclined rectangular cells was studied. The cell walls are thin, and the hot and cold surfaces are isothermal. The two-dimensional natural convection problem was solved using finite difference techniques. The parameters studied were cell aspect ratios (A) of 0.5 and 1, Rayleigh numbers (Ra) up to 105, a Prandtl number (Pr) of 0.72 and a tilt angle (φ) of 60 deg. These parameters are of interest in solar collectors. The numerical results are substantiated by experimental results. It was found that convection coefficients for cells with adiabatic walls are substantially higher than those for cells with conducting walls. Correlations are given for estimating the convective heat transfer across the cell and the conductive heat transfer across the cell wall. These correlations are compared with available experimental and numerical work of other authors.

scholarly journals Effect of corrugated minichannel variable width on entropy generation for convective heat transfer of alpha-Alumina-water nanofluid

2021 ◽  
Vol 2053 (1) ◽  
pp. 012016
Author(s):  
N M Muhammad ◽  
N A C Sidik ◽  
A Saat ◽  
Y Asako ◽  
W M A A Japar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Entropy Production ◽  
Convective Heat ◽  
Entropy Generation ◽  
Entropy Generation Rate ◽  
Thermal Systems ◽  
Volume Fractions ◽  
Thermal Entropy ◽  
Alpha Alumina

Abstract Energy management and sustainability in thermal systems require maximum utilization of resources with minimal losses. However, it is rarely unattainable due to the ever-increasing need for a high-performance system combined with device size reduction. The numerical study examined convective heat transfer of an alpha-Alumina-water nanofluid in variable-width corrugated minichannel heat sinks. The objective is to study the impact of nanoparticle volume fractions and flow area variation on the entropy generation rate. The determining variables are 0.005 – 0.02 volume fractions, the fluid velocity 3 – 5.5 m/s and heat flux of 85 W/cm2. The numerical results show an acceptable correlation with the experiment results. The results indicate the thermal entropy production drop with an increase in nanoparticles volume fraction. Contrastingly, the frictional resistance entropy suggests the opposite trend due to the turbulence effect on the fluid viscosity. The induction of Alumina-Water nanofluid with enhanced thermal conductivity declined the entropy generation rate compared to water alone. The increase in width ratio by 16% between the cases translates to at least a 9% increase in thermal entropy production. The outcome of this study can provide designers and operators of thermal systems more insight into entropy management in corrugated heatsinks.

Effect of Edge Conditions on Natural Convective Heat Transfer From a Narrow Vertical Flat Plate With a Uniform Surface Heat Flux

2007 ◽  
Author(s):  
Patrick H. Oosthuizen ◽  
Jane T. Paul
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Surface Heat Flux ◽  
Three Dimensional ◽  
Surface Heat ◽  
Heated Plate ◽  
Two Dimensional ◽  
Adiabatic Surface

Two-dimensional natural convective heat transfer from vertical plates has been extensively studied. However, when the width of the plate is relatively small compared to its height, the heat transfer rate can be greater than that predicted by these two-dimensional flow results. Because situations that can be approximately modelled as narrow vertical plates occur in a number of practical situations, there exists a need to be able to predict heat transfer rates from such narrow plates. Attention has here been given to a plate with a uniform surface heat flux. The magnitude of the edge effects will, in general, depend on the boundary conditions existing near the edge of the plate. To examine this effect, two situations have been considered. In one, the heated plate is imbedded in a large plane adiabatic surface, the surfaces of the heated plane and the adiabatic surface being in the same plane while in the second there are plane adiabatic surfaces above and below the heated plate but the edge of the plate is directly exposed to the surrounding fluid. The flow has been assumed to be steady and laminar and it has been assumed that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces, this having been treated by using the Boussinesq approach. It has also been assumed that the flow is symmetrical about the vertical centre-plane of the plate. The solution has been obtained by numerically solving the full three-dimensional form of the governing equations, these equations being written in terms of dimensionless variables. Results have only been obtained for a Prandtl number of 0.7. A wide range of the other governing parameters have been considered for both edge situations and the conditions under which three dimensional flow effects can be neglected have been deduced.

Large-Eddy Simulation of Flow and Convective Heat Transfer in a Gas Turbine Can Combustor With Synthetic Inlet Turbulence

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Sunil Patil ◽  
Danesh Tafti
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Computational Time ◽  
Computational Domain ◽  
Rans Simulation ◽  
Eddy Simulation ◽  
Large Eddy

Large eddy simulations of swirling flow and the associated convective heat transfer in a gas turbine can combustor under cold flow conditions for Reynolds numbers of 50,000 and 80,000 with a characteristic Swirl number of 0.7 are carried out. A precursor Reynolds averaged Navier-Stokes (RANS) simulation is used to provide the inlet boundary conditions to the large-eddy simulation (LES) computational domain, which includes only the can combustor. A stochastic procedure based on the classical view of turbulence as a superposition of the coherent structures is used to simulate the turbulence at the inlet plane of the computational domain using the mean flow velocity and Reynolds stress data from the precursor RANS simulation. To further reduce the overall computational resource requirement and the total computational time, the near wall region is modeled using a zonal two layer model (WMLES). A novel formulation in the generalized co-ordinate system is used for the solution of effective tangential velocity and temperature in the inner layer virtual mesh. The WMLES predictions are compared with the experimental data of Patil et al. (2011, “Experimental and Numerical Investigation of Convective Heat Transfer in Gas Turbine Can Combustor,” ASME J. Turbomach., 133(1), p. 011028) for the local heat transfer distribution on the combustor liner wall obtained using robust infrared thermography technique. The heat transfer coefficient distribution on the liner wall predicted from the WMLES is in good agreement with experimental values. The location and the magnitude of the peak heat transfer are predicted in very close agreement with the experiments.

Development and validation of an incompressible Navier-Stokes solver including convective heat transfer

2015 ◽  
Vol 25 (4) ◽  
pp. 861-886 ◽  
Author(s):  
Konstantinos Stokos ◽  
Socrates Vrahliotis ◽  
Theodora Pappou ◽  
Sokrates Tsangaris
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Laminar Flows ◽  
Navier Stokes ◽  
Content Type ◽  
Strongly Coupled ◽  
Loosely Coupled ◽  
Wide Range ◽  
Coupled Solution

Purpose – The purpose of this paper is to present a numerical method for the simulation of steady and unsteady incompressible laminar flows, including convective heat transfer. Design/methodology/approach – A node centered, finite volume discretization technique is applied on hybrid meshes. The developed solver, is based on the artificial compressibility approach. Findings – A sufficient number of representative test cases have been examined for the validation of this numerical solver. A wide range of the various dimensionless parameters were applied for different working fluids, in order to estimate the general applicability of our solver. The obtained results agree well with those published by other researchers. The strongly coupled solution of the governing equations showed superiority compared to the loosely coupled solution as inviscid effects increase. Practical implications – Convective heat transfer is dominant in a wide variety of practical engineering problems, such as cooling of electronic chips, design of heat exchangers and fire simulation and suspension in tunnels. Originality/value – A comparison between the strongly coupled solution and the loosely coupled solution of the Navier-Stokes and energy equations is presented. A robust upwind scheme based on Roe’s approximate Riemann solver is proposed.

An Experimental Study of Convective Heat Transfer in Radially Rotating Rectangular Ducts

1991 ◽  
Vol 113 (3) ◽  
pp. 604-611 ◽  
Author(s):  
C. Y. Soong ◽  
S. T. Lin ◽  
G. J. Hwang
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Rotational Speed ◽  
Main Flow ◽  
Buoyancy Flow ◽  
Aspect Ratios

The paper presents an experimental study of convective heat transfer in radially rotating isothermal rectangular ducts with various height and width aspect ratios. The convective heat transfer is affected by secondary flows resulting from Coriolis force and the buoyancy flow, which is in turn due to the centrifugal force in the duct. The growth and strength of the secondary flow depend on the rotational Reynolds number; the effect of the buoyancy flow is characterized by the rotational Rayleigh number. The aspect ratio of the duct may affect the secondary flow and the buoyancy flow, and therefore is also a critical parameter in the heat transfer mechanism. In the present work the effects of the main flow, the rotational speed, and the aspect ratio γ on heat transfer are subjects of major interest. Ducts of aspect ratios γ=5, 2, 1, 0.5, and 0.2 at rotational speed up to 3000 rpm are studied. The main flow Reynolds number ranges from 700 to 20,000 to cover the laminar, transitional, and turbulent flow regimes in the duct flow. Test data and discussion are presented.

Convective Heat Transfer From a Sphere Due to Acoustic Streaming

1993 ◽  
Vol 115 (2) ◽  
pp. 332-341 ◽  
Author(s):  
A. Gopinath ◽  
A. F. Mills
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Acoustic Streaming ◽  
Reynolds Numbers ◽  
Materials Processing ◽  
Acoustic Levitation ◽  
Simple Experiment ◽  
Wide Range ◽  
Prandtl Numbers

Convective heat transfer from a sphere due to acoustic streaming is examined for large streaming Reynolds numbers. Analytical and numerical solution techniques are used to obtain Nusselt number correlations for a wide range of Prandtl numbers with particular emphasis on the case of Pr~1. A simple experiment performed to confirm some of the predictions is described. The results obtained can be used for the thermal analysis of containerless materials processing in space using acoustic levitation.

Optimization of Heat Transfer Rate in the Rectangular Microchannel of Different Aspect Ratios With Constant Cross Sectional Area

2008 ◽  
Author(s):  
F. Kowsary ◽  
N. Noroozi ◽  
M. Rezaei Barmi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Reynolds Numbers ◽  
Cross Sectional Area ◽  
Heat Sinks ◽  
Sectional Area ◽  
Cross Sectional ◽  
Aspect Ratios

The increased power dissipation and reduced dimensions of microelectronics devices have emphasized the need for highly efficient compact cooling technologies. Microchannel heat sinks are of particular interest due to the very high rates of heat transfer they enable in conjunction with greatly reduced heat sink length scales and coolant mass flow rate. Therefore, in the present work, optimization of laminar convective heat transfer in the microchannel heat sinks is investigated for uniform heat flux and different cross sectional areas of different aspect ratios. Three-dimensional numerical simulations of general form of energy equation were performed to predict Nusselt number in the laminar flow regime. Using these results, an optimum forced convective heat transfer coefficient was computed for several cross sectional areas and Reynolds numbers, utilizing the univariable search method. Different aspect ratios have different influences on Nusselt number in thermally developing and fully developed regions for different cross sectional areas and Reynolds numbers. There exists an optimum Nusselt number for each Reynolds number and cross sectional area by varying aspect ratio. Thus, optimized state is computed and related graphs are presented.

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