Heat Transfer Enhancement of Heat Sources at its Optimum Position in a Square Enclosure with Ventilation Ports

2021 ◽  
Vol 406 ◽  
pp. 12-24
Author(s):  
Fatima Zohra Benouis ◽  
Ould Amer Yacine
Keyword(s):  
Heat Transfer ◽  
Control Volume ◽  
Reynolds Numbers ◽  
Heat Sources ◽  
Governing Equations ◽  
Transfer Enhancement ◽  
Square Enclosure ◽  
Cooling Strategy ◽  
Optimum Position ◽  
Volume Method

Forced convection in a ventilated enclosure with aspect ratio 2 is studied. Three heat sources simulating electronic component are placed in the bottom wall of the cavity, all walls are kept insulated. With varying the inlet and the outlet location of cold air firstly then swapping the location of the heat sources, the optimal cooling strategy was identified. Consideration was given to steady two-dimensional laminar flow and Reynolds number (Re) in the range 10–1500. The governing equations along with the boundary conditions are solved by using the control volume method. Calculations showed that enhancement in heat transfer occurred, and the results indicate that there exists an optimal location of ventilation ports and an optimal disposition of heat sources for which the heat transfer is maximized for all ranges of Reynolds numbers.

Effect of moving stretching sheets on natural convection in partially heated square cavity filled with nanofluid

2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Anil Kumar ◽  
Pentyala Srinivasa Rao
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Buoyancy Force ◽  
Volume Fraction ◽  
Governing Equations ◽  
Transfer Enhancement ◽  
Square Cavity ◽  
Flow Strength ◽  
Square Enclosure ◽  
Dimensionless Velocity

Abstract This article deals with the heat transfer enhancement due to buoyancy force in a partially heated square enclosure filled with nanofluids. The model is developed to analyse the behaviour of nanofluids taking into account of volume fraction and stretching parameter, when square horizontal walls are moving in opposite directions to each other. Implicit alternate direct finite difference method has been used to solve the governing equations of vorticity, energy, and kinematics. Graphically investigated the effect of physical pertinent controlling parameters on the dimensionless velocity, streamlines, isothermal, and Nusselt number. The obtained numerical solution achieves the best configuration for Rayleigh number 103 ≤ Ra ≤ 105, stretching parameter 0 ≤ τ ≤ 2.5, and volume fraction 0 ≤ ϕ ≤ 0.2. It is found that the stretching parameter and direction of moving walls affect the fluid flow, flow strength, and heat transfer in the cavity.

Flow in a Corrugated Channel With Multiple Heat Sources

2008 ◽  
Author(s):  
Esam M. Alawadhi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Reynolds Numbers ◽  
Heat Sources ◽  
The Finite Element Method ◽  
Transfer Enhancement ◽  
Wavy Channel ◽  
Discrete Heat Sources ◽  
Minimum Cross Section ◽  
High Reynolds

Numerical method based on the finite element method is utilized to study the heat transfer enhancement from discrete heat sources using a wavy channel. The considered geometry consists of a channel formed by two wavy plates with six discrete heat sources placed on upper and lower walls. The effect of the Reynolds number, Prandtl number, waviness of the wavy wall, and the location of the heat sources on the heat transfer out of the heat sources is investigated. The result indicates that the wavy channel significantly enhances the heat flow out of the heat sources, and heat sources located at the minimum cross section areas of the channel shows the best performance. The heat transfer enhancement can reaches as high as 120% for high Reynolds numbers and waviness of the channel.

scholarly journals Nanofluid Convective Heat Transfer Enhancement Elliptical Tube inside Circular Tube under Turbulent Flow

2018 ◽  
Vol 23 (4) ◽  
pp. 78
Author(s):  
Suad Danook ◽  
Qusay Jasim ◽  
Adnan Hussein
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Transfer Rate ◽  
Circular Tube ◽  
Uniform Heat Flux ◽  
Governing Equations ◽  
Transfer Enhancement ◽  
Enhance Heat Transfer ◽  
Electrical Heater ◽  
Volume Method

Heat transfer enhancement employing an elliptical tube inside a circular tube to increase the heat transfer rate without increasing in pressure drop is investigated. The flow rate inside the narrow is in the range of Reynolds number 10,000 to 100,000. Commercial software is used to solve the governing equations (continuity, momentum, and energy) by adopting a finite volume method (FVM). The electrical heater is connected around the circular tube to apply uniform heat flux (3000 W/m2) as a boundary condition. The volume concentrations are in the range of 0.25% to 1% with different TiO2 nanoparticle diameters in the range of 27 nm to 50 nm dispersed in water. The results indicate that the elliptical annulus tube can enhance heat transfer and friction factor by approximately 19% and 6% than the circular tube respectively. Results show that the heat transfer enhancement is significantly increasing as the volume concentrations increase and the nanoparticles size diameter decrease.

An Experimental and Numerical Study of Heat Transfer and Pressure Loss in a Rectangular Channel With V-Shaped Ribs

2006 ◽  
Author(s):  
Michael Maurer ◽  
Jens von Wolfersdorf ◽  
Michael Gritsch
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Pressure Loss ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Transfer Enhancement ◽  
High Reynolds Numbers ◽  
High Reynolds

An experimental and numerical study was conducted to determine the thermal performance of V-shaped ribs in a rectangular channel with an aspect ratio of 2:1. Local heat transfer coefficients were measured using the steady state thermochromic liquid crystal technique. Periodic pressure losses were obtained with pressure taps along the smooth channel sidewall. Reynolds numbers from 95,000 to 500,000 were investigated with V-shaped ribs located on one side or on both sides of the test channel. The rib height-to-hydraulic diameter ratios (e/Dh) were 0.0625 and 0.02, and the rib pitch-to-height ratio (P/e) was 10. In addition, all test cases were investigated numerically. The commercial software FLUENT™ was used with a two-layer k-ε turbulence model. Numerically and experimentally obtained data were compared. It was determined that the heat transfer enhancement based on the heat transfer of a smooth wall levels off for Reynolds numbers over 200,000. The introduction of a second ribbed sidewall slightly increased the heat transfer enhancement whereas the pressure penalty was approximately doubled. Diminishing the rib height at high Reynolds numbers had the disadvantage of a slightly decreased heat transfer enhancement, but benefits in a significantly reduced pressure loss. At high Reynolds numbers small-scale ribs in a one-sided ribbed channel were shown to have the best thermal performance.

scholarly journals The Influence of Different Types of Nanofluid on Thermal and Fluid Flow Performance of Liquid Cold Plate

2018 ◽  
Vol 7 (4.35) ◽  
pp. 148 ◽  
Author(s):  
Nur Irmawati Om ◽  
Rozli Zulkifli ◽  
P. Gunnasegaran
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Steady State ◽  
Pressure Drop ◽  
Volume Fraction ◽  
Cold Plate ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Different Types ◽  
Volume Method

The influence of utilizing different nanofluids types on the liquid cold plate (LCP) is numerically investigated. The thermal and fluid flow performance of LCP is examined by using pure ethylene glycol (EG), Al2O3-EG and CuO-EG. The volume fraction of the nanoparticle for both nanofluid is 2%. The finite volume method (FVM) has been used to solved 3-D steady state, laminar flow and heat transfer governing equations. The presented results indicate that Al2O3-EG able to provide the lowest surface temperature of the heater block followed by CuO-EG and EG, respectively. It is also found that the pressure drop and friction factor are higher for Al2O3-EG and CuO-EG compared to the pure EG.

Experimental Investigation Into the Influence of Varying Stagger on the Performance of a Pin-Fin Array

2008 ◽  
Author(s):  
W. D. Allan ◽  
S. A. Andrews ◽  
M. LaViolette
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Pressure Loss ◽  
Reynolds Numbers ◽  
Design Criterion ◽  
Transfer Enhancement ◽  
Pin Fin ◽  
Line Array ◽  
Array Performance ◽  
Pin Fin Array

A six row pin-fin array was constructed with a spanwise spacing of 2.5 diameters, streamwise spacing of 1.5 diameters and a height to diameter ratio of 1. The streamwise stagger of alternate rows was continuously varied from fully in-line to fully staggered. Tests were carried out at Reynolds numbers of 2.7 × 104 and 2.3 × 104, corresponding to maximum velocities, in the low subsonic range, of 21 m/s and 18 m/s respectively. These results showed that the array averaged heat transfer was greatest from a fully staggered array and had a minimum at a stagger slightly greater than fully in-line. However, with increasing stagger, the array-averaged friction factor grew at a greater rate than the heat transfer. The ensuing analysis of the total array performance, considering both the magnitude of heat transfer and the losses within the array, showed that the fully in-line array had the highest ratio of heat transfer enhancement to friction factor enhancement. Therefore, if pressure loss was a design criterion, the fully in-line array was preferable. However, if pressure loss was not a constraint, then the staggered array was preferable.

A Numerical Study of Heat Transfer and Flow Structure in Channels With Miniature V Rib-Dimple Hybrid Structure on One Wall

2018 ◽  
Author(s):  
Peng Zhang ◽  
Yu Rao ◽  
Yanlin Li
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Hybrid Structure ◽  
Transfer Enhancement ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Flow Mixing

This paper presents a numerical study on turbulent flow and heat transfer in the channels with a novel hybrid cooling structure with miniature V-shaped ribs and dimples on one wall. The heat transfer characteristics, pressure loss and turbulent flow structures in the channels with the rib-dimples with three different rib heights of 0.6 mm, 1.0 mm and 1.5 mm are obtained for the Reynolds numbers ranging from 18,700 to 60,000 by numerical simulations, which are also compared with counterpart of a pure dimpled and pure V ribbed channel. The results show that the overall Nusselt numbers of the V rib-dimple channel with the rib height of 1.5 mm is up to 70% higher than that of the channels with pure dimples. The numerical simulations show that the arrangement of the miniature V rib upstream each dimple induces complex secondary flow near the wall and generates downwashing vortices, which intensifies the flow mixing and turbulent kinetic energy in the dimple, resulting in significant improvement in heat transfer enhancement and uniformness.

Effect of Periodic Imposed Heat Flux on Three-Dimensional Natural Convection in a Partially Heated Cubical Enclosure

2016 ◽  
Vol 831 ◽  
pp. 83-91
Author(s):  
Lahoucine Belarche ◽  
Btissam Abourida
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Cubical Enclosure ◽  
Simplec Algorithm ◽  
Volume Method

The three-dimensional numerical study of natural convection in a cubical enclosure, discretely heated, was carried out in this study. Two heating square sections, similar to the integrated electronic components, are placed on the vertical wall of the enclosure. The imposed heating fluxes vary sinusoidally with time, in phase and in opposition of phase. The temperature of the opposite vertical wall is maintained at a cold uniform temperature and the other walls are adiabatic. The governing equations are solved using Control volume method by SIMPLEC algorithm. The sections dimension ε = D / H and the Rayleigh number Ra were fixed respectively at 0,35 and 106. The average heat transfer and the maximum temperature on the active portions will be examined for a given set of the governing parameters, namely the amplitude of the variable temperatures a and their period τp. The obtained results show significant changes in terms of heat transfer, by proper choice of the heating mode and the governing parameters.

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