Enhanced Cooling of Electronic Components Using Fluid Flow Under High Adverse Pressure Gradient

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
S. Ravishankar ◽  
K. Arul Prakash
Keyword(s):  
Heat Transfer ◽  
Adverse Pressure Gradient ◽  
Circuit Board ◽  
Heated Wall ◽  
Recirculation Region ◽  
Electronic Systems ◽  
Governing Equations ◽  
Galerkin Finite Element ◽  
Flow And Heat Transfer ◽  
Very High

Heat transfer in electronic systems is studied by simulating flow in a two pass channel with the divider representing a circuit board. Bypass holes are introduced on the circuit board to obtain detailed physical insights of the reversed flows in the second pass and thereby improve the cooling effect. The time-dependent governing equations are solved using an in-house code based on Streamline upwind/Petrov-Galerkin finite element method for Reynolds number ranging from 100 to 900. It is observed that stagnant zones are formed in the return path along the upper heated wall due to the formation of primary recirculation region on the divider plate. These stagnant zones are convected downstream by introducing bypass slots thereby enhancing the convective cooling. A parametric study on the location and number of bypass slots reveals that for a particular combination, the flow becomes unsteady thereby the heat transfer is increased. The presence of multiple slot jets also reduces the overall pressure drop required to drive the flow and heat transfer is very high at the point of impingement between the slots.

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.

Passive Heat Transfer in Porous Enclosures Using a Two-Energy Equation Model

2012 ◽  
Author(s):  
Marcelo J. S. deLemos ◽  
Paulo H. S. Carvalho
Keyword(s):  
Heat Transfer ◽  
Energy Equation ◽  
Equation Model ◽  
Thermal Conductivity Ratio ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Energy Models ◽  
Different Temperatures ◽  
Volume Method ◽  
Generalized Coordinate

This paper presents computations for natural convection within a porous cavity filled with a fluid saturated permeable medium. The finite volume method in a generalized coordinate system is applied. The walls are maintained at constant but different temperatures, while the horizontal walls are kept insulated. Governing equations are written in terms of primitive variables and are recast into a general form. Flow and heat transfer characteristics are investigated for two energy models and distinct solid-to-fluid thermal conductivity ratio.

Computational Study of Streamfunction-Vorticity Formulation of Incompressible Flow and Heat Transfer Problems

2011 ◽  
Vol 52-54 ◽  
pp. 511-516 ◽  
Author(s):  
Arup Kumar Borah
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Boundary Conditions ◽  
Incompressible Flow ◽  
Computational Study ◽  
The Other ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Continuity Constraint ◽  
Transfer Problems

In this paper we have studied the streamfunction-vorticity formulation can be advantageously used to analyse steady as well as unsteady incompressible flow and heat transfer problems, since it allows the elimination of pressure from the governing equations and automatically satisfies the continuity constraint. On the other hand, the specification of boundary conditions for the streamfunction-vorticity is not easy and a poor evaluation of these conditions may lead to serious difficulties in obtaining a converged solution. The main issue addressed in this paper is the specification in the boundary conditions in the context of finite element of discretization, but approach utilized can be easily extended to finite volume computations.

On Suddenly Expanding Non-Isothermal Pipe Flows of a Bingham Fluid

1999 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Heat Transfer ◽  
Newtonian Fluid ◽  
Transfer Problem ◽  
Numerical Technique ◽  
Complex Nature ◽  
Brinkman Number ◽  
Governing Equations ◽  
Heat Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Pipe Expansion

Abstract The non-isothermal laminar flow of the Bingham non-Newtonian fluid through a sudden pipe expansion is investigated. The governing equations of conservation of mass, momentum and energy are solved using the finite-difference numerical technique. The effects of non-dimensional yield stress, Reynolds number, Prandtl number and Brinkman number on the flow and heat transfer characteristics are studied. The obtained results indicate the complex nature of the present non-Newtonian fluid flow and heat transfer problem and reveal new features not encountered in the case of Newtonian fluids.

scholarly journals Transient free convection in an inclined square porous cavity filled with a nanofluid using LTNE and Buongiorno’s models

2018 ◽  
Vol 240 ◽  
pp. 03014
Author(s):  
Mikhail Sheremet ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Inclination Angle ◽  
Equilibrium Temperature ◽  
Brownian Diffusion ◽  
Governing Equations ◽  
Nanofluid Flow ◽  
Porous Cavity ◽  
Flow And Heat Transfer ◽  
The Finite Difference Method ◽  
Porous Enclosure

The combined effect of Brownian diffusion, thermophoresis and cavity inclination angle on natural convective heat transfer in an inclined porous enclosure has been studied numerically. Fluid containing nanoparticles of low concentration circulates inside the cavity under the effect of the buoyancy force. Governing equations with corresponding boundary conditions formulated using the non-dimensional stream function and vorticity variables have been solved by the finite difference method. An influence of the cavity inclination angle, Darcy and Nield numbers on nanofluid flow and heat transfer has been investigated. It has been found that high Nield numbers illustrate more equilibrium temperature distribution inside the porous cavity.

Research on Heat and Mass Transfer of Flat Grooved Heat Pipes

2015 ◽  
Vol 733 ◽  
pp. 599-602
Author(s):  
Lei Cao ◽  
Guo Chang Zhao ◽  
Li Ping Song ◽  
Tian Dong Lu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Temperature Control ◽  
Experimental Studies ◽  
Heat Pipes ◽  
Electronic Systems ◽  
Temperature Uniformity ◽  
Flat Surfaces ◽  
Flow And Heat Transfer ◽  
High Degree

Flat grooved heat pipes, which are especially useful in obtaining a high degree of temperature uniformity on flat surfaces, have been successfully used in the temperature control of electronic systems, however, the mechanisms governing the flow and heat transfer of this kind of heat pipes are still under scrutiny as some reported results cannot be reproduced by others or some assumptions have been proven to be unreasonable or ideal. The theoretical and experimental studies on flat grooved heat pipes and introduce work performed on modeling flat grooved heat pipes are reviewed in this paper.

Separation of Natural Convection and Radiation by Changing Rotational Acceleration

Volume 1 ◽  
2004 ◽  
Author(s):  
Arnout Willockx ◽  
Gilbert De Mey ◽  
Michel De Paepe ◽  
Boguslaw Wiecek ◽  
Mariusz Felczak ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Centripetal Force ◽  
Rotational Acceleration ◽  
Governing Equations ◽  
Total Heat Transfer ◽  
Closed Cavity ◽  
Printed Circuit

The objective is to separate natural convection and radiation experimentally. Therefore a heat source is placed inside a closed cavity and the acceleration inside the cavity can be changed. A centrifuge is used to change the acceleration. A flat resistor etched on a printed circuit board of 10mm × 48mm, is placed in a hermetically sealed cylinder, which hangs under the arm of the centrifuge. The resistor is powered by a battery, dissipates 0,35W and has a surface temperature of 60°C at 1g. Natural convection is maintained inside the cylinder. Conduction is reduced to a negligible amount by construction of the experiment, thus convection and radiation are the main modes of heat transfer. The rotational speed of the centrifuge determines the centrifugal force in the cylinder. When the centripetal force increases, the temperature of the resistor decreases due to the increase of natural convection. The amount of radiation and total heat transfer can be determined from the experiment, so the amount of natural convection can also be determined. The experimental results are compared with the governing equations to validate the experiment. The reproducibility of the experiment is also checked.

scholarly journals Fractional Boundary Layer Flow and Heat Transfer Over a Stretching Sheet With Variable Thickness

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Lin Liu ◽  
Liancun Zheng ◽  
Yanping Chen ◽  
Fawang Liu
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Stretching Sheet ◽  
Magnetic Parameter ◽  
Governing Equations ◽  
Velocity Boundary Layer ◽  
Flow And Heat Transfer ◽  
Temperature Boundary ◽  
Layer Flow ◽  
Fractional Parameter

The paper gives a comprehensive study on the space fractional boundary layer flow and heat transfer over a stretching sheet with variable thickness, and the variable magnetic field is applied. Novel governing equations with left and right Riemann–Liouville fractional derivatives subject to irregular region are formulated. By introducing new variables, the boundary conditions change as the traditional ones. Solutions of the governing equations are obtained numerically where the shifted Grünwald formulae are applied. Good agreement is obtained between the numerical solutions and exact solutions which are constructed by introducing new source items. Dynamic characteristics with the effects of involved parameters on the velocity and temperature distributions are shown and discussed by graphical illustrations. Results show that the velocity boundary layer is thicker for a larger fractional parameter or a smaller magnetic parameter, while the temperature boundary layer is thicker for a larger fractional parameter, a smaller exponent parameter, or a larger magnetic parameter. Moreover, it is thicker at a smaller y and thinner at a larger y for the velocity boundary layer with a larger exponent parameter while for the velocity and temperature boundary layers with a smaller weight coefficient.

Thermal Fluid Flow Transport Characteristics in Confined Channels With Two-Dimensional Dual Jet Impingement

2011 ◽  
Author(s):  
Caner Senkal ◽  
Shuichi Torii
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Rate ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Velocity Ratio ◽  
Heated Wall ◽  
Outer Diameter ◽  
Stagnation Zone ◽  
Governing Equations

The flow and heat transfer characteristics of laminar dual circular jet impinging on a heating plate with inclined confinement surface has been investigated numerically. Governing equations in steady state are solved by a control volume based finite-difference method. The simulations have been carried out for Reynolds number (250≤Re≤418), the angle of inclination of the confined upper wall (0 ≤ θ ≤ 10), circular jet to annular jet velocity ratio (0≤VR≤2) and jet to target plate distances between 2D and 8D where D is the outer diameter of dual jet.SIMPLE algorithm was used to obtain velocity and temperature fields. Hybrid difference scheme is adopted for the discretized terms in the governing equations. The discretised equations are solved iteratively using the tridiagonal matrix algorithm line solver. Heat transfer performance along the heated wall is amplified with an increase in the velocity ratio and the Reynolds number. On the contrary, a substantial reduction in the heat transfer rate, for VR = 0.0, occurs in the stagnation zone, because the absence of the inner nozzle injection causes the recirculation in the corresponding region. The heat transfer rate in the stagnation zone is attenuated by increasing the jet nozzle to impinging plate distance. In particular, the effect of the inclination angle in the down-stream region, especially at the vicinity of outlet, is major then other effects Nusselt number distribution on the impingement plate is affected by inclined upper wall because inclination of the wall accelerates the exhaust flow. The streamwise reduction in the heat transfer rate for θ = 0° is suppressed by the presence of the inclined confinement surface and its value is intensified by the inclination angle.

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