scholarly journals Numerical Simulation of the Cooling of Heated Electronic Blocks in Horizontal Channel by Mixed Convection of Nanofluids

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Mustapha Ait Hssain ◽  
Rachid Mir ◽  
Youness El Hammami
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Volume Fraction ◽  
Numerical Study ◽  
Solid Volume Fraction ◽  
Simple Algorithm ◽  
Separation Distance ◽  
Horizontal Channel ◽  
Laminar Mixed Convection ◽  
Finite Volume Approach

The present work is devoted to the numerical study of steady and laminar mixed convection of nanofluid (water nanoparticles) in a horizontal channel provided with sources of heat at constant temperature, which simulate hot electronic components. The transport equations for continuity, momentum, and energy are solved with finite volume approach using the SIMPLE algorithm. The effective thermal conductivity and the dynamic viscosity of the nanofluid are calculated using, respectively, the Maxwell-Garnett and Brinkman model. The influence of the volume fraction of the nanoparticles 0%≤φ≤10%, Reynolds numbers 5≤Re≤75, the distance between the blocks 0≤d/H≤3, and the types of nanoparticles added (TiO2, Al2O3, CuO, Ag, Cu, and MgO) were investigated and discussed. It emerges from this simulation that the heat transfer increases with the increase in the volume fraction of the nanoparticles and the Reynolds number and decreases with the augmentation of separation distance between heated sources. Moreover, the study shows that the heat transfer is improved by 20% at a solid volume fraction of 10% of Cu nanoparticles.

Numerical Simulation of Nanofluid-Cooling Enhancement of Three Fins Mounted in a Horizontal Channel

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Moussa Khentoul ◽  
Rachid Bessaïh
Keyword(s):  
Volume Fraction ◽  
Numerical Study ◽  
Solid Volume Fraction ◽  
Horizontal Channel ◽  
Thermal Fields ◽  
Nusselt Numbers ◽  
Simpler Algorithm ◽  
Laminar Mixed Convection ◽  
Cooling Enhancement ◽  
Volume Method

This article presents a numerical study of two-dimensional laminar mixed convection in a horizontal channel. The upper horizontal wall of the channel is insulated. The governing equations were solved by using the finite volume method based on the simpler algorithm. Comparisons with previous results were performed and found to be in excellent agreement. The results were presented in terms of streamlines, isotherms, local and average Nusselt numbers for the Richardson number (0 ≤ Ri ≤ 10), Reynolds number (5 ≤ Re ≤ 100), solid volume fraction of nanoparticles (0 ≤ ϕ ≤ 0.10), and the type of nanofluids (Cu, Ag, Al2O3, and TiO2). The results show that the previous parameters have considerable effects on the flow and thermal fields. It was found that the heat transfer increases with increasing of Ra, Re, and ϕ.

Heat transfer and entropy generation analysis of Cu-water nanofluid in a vertical channel

2018 ◽  
Vol 15 (5) ◽  
pp. 604-613
Author(s):  
Essma Belahmadi ◽  
Rachid Bessaih
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Mixed Convection ◽  
Friction Factor ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Vertical Channel ◽  
Simple Algorithm ◽  
Content Type

Purpose The purpose of this study is to analyze heat transfer and entropy generation of a Cu-water nanofluid in a vertical channel. The channel walls are maintained at a hot temperature Tw. An up flow penetrates the channel at a uniform velocity v0 and a cold temperature T0 (T0 < Tw). The effects of Reynolds number Re, Grashof number Gr and solid volume fraction ϕ on streamlines, isotherms, entropy generation, friction factor, local and mean Nusselt numbers are evaluated. Design/methodology/approach The Cu-water nanofluid is used in this study. The software Ansys-fluent 14.5, based on the finite-volume method and SIMPLE algorithm, is used to simulate the mixed convection problem with entropy generation in a vertical channel. Findings The results show that the increase of Reynolds and Grashof numbers and solid volume fraction improves heat transfer and reduces entropy generation. Correlations for the mean Nusselt number and friction factor in terms of Reynolds number and solid volume fraction are obtained. The present results are compared with those found in the literature, which reveal a very good agreement. Originality/value The originality of this work is to understand the heat transfer and entropy generation for mixed convection of a Cu-water nanofluid in a vertical channel.

scholarly journals Numerical analysis of mixed convection characteristics inside a ventilated cavity including the effects of nanoparticle suspensions

2017 ◽  
Vol 21 (5) ◽  
pp. 2205-2215
Author(s):  
Ehsan Sourtiji ◽  
Mofid Gorji-Bandpy
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Mixed Convection ◽  
Volume Fraction ◽  
Numerical Study ◽  
Solid Volume Fraction ◽  
Maximum Heat ◽  
Outlet Port ◽  
Maximum Heat Transfer

A numerical study of mixed convection flow and heat transfer inside a square cavity with inlet and outlet ports is performed. The position of the inlet port is fixed but the location of the outlet port is varied along the four walls of the cavity to investigate the best position corresponding to maximum heat transfer rate and minimum pressure drop in the cavity. It is seen that the overall Nusselt number and pressure drop coefficient vary drastically depending on the Reynolds and Richardson numbers and the position of the outlet port. As the Richardson number increases, the overall Nusselt number generally rises for all cases investigated. It is deduced that placing the outlet port on the right side of the top wall is the best position that leads to the greatest overall Nusselt number and lower pressure drop coefficient. Finally, the effects of nanoparticles on heat transfer are investigated for the best position of the outlet port. It is found that an enhancement of heat transfer and pressure drop is seen in the presence of nanoparticles and augments with solid volume fraction of the nanofluid. It is also observed that the effects of nanoparticles on heat transfer at low Richardson numbers is more than that of high Richardson numbers. <br><br><font color="red"><b> This article has been retracted. Link to the retraction <u><a href="http://dx.doi.org/10.2298/TSCI190625278E">10.2298/TSCI190625278E</a><u></b></font>

scholarly journals Numerical study of mixed convection heat transfer in lid-driven cavity utilizing nanofluid: Effect of type and model of nanofluid

2015 ◽  
Vol 19 (5) ◽  
pp. 1575-1590 ◽  
Author(s):  
Nader Pourmahmoud ◽  
Ashkan Ghafouri ◽  
Iraj Mirzaee
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Volume Fraction ◽  
Numerical Study ◽  
Published Data ◽  
Driven Cavity ◽  
Laminar Mixed Convection ◽  
Special Cases

Numerical investigation of the laminar mixed convection in two-dimensional lid driven cavity filled with water-Al2O3, water-Cu or water-TiO2 nanofluids is done in this work. In the present study, the top and bottom horizontal walls are thermally insulated while the vertical walls are kept at constant but different temperatures. The governing equations are given in term of the stream function-vorticity formulation in the non-dimensionalized form and then solved numerically by second-order central difference scheme. The thermal conductivity and effective viscosity of nanofluid have been calculated by Maxwell-Garnett and Brinkman models, respectively. An excellent agreement between the current work and previously published data on the basis of special cases are found. The governing parameters are Rayleigh number 103 ? Ra ? 106 and solid concentration 0 ? ? ?0.2 at constant Reynolds and Prandtl numbers. An increase in mean Nusselt number is found as the volume fraction of nanoparticles increases for the whole range of Rayleigh numbers. In addition, it is found that significant heat transfer enhancement can be obtained by increasing thermal conductivity coefficient of additive particles. At Ra=1.75?105, the Nusselt number increases by about 21% for TiO2-Water, and almost 25% for Al2O3-Water, and finally around 40% for Cu-Water nanofluid. Therefore, the highest values are obtained when using Cu nanoparticles. The result obtained using variable thermal conductivity and variable viscosity models are also compared to the results acquired by the Maxwell-Garnett and the Brinkman model.

scholarly journals Numerical Study of Mixed Convection of the Nanofluids in Two-Sided Lid-Driven Square Cavity with a Pair of Triangular Heating Cylinders

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Zoubair Boulahia ◽  
Abderrahim Wakif ◽  
Rachid Sehaqui
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Numerical Study ◽  
Simple Algorithm ◽  
Design Parameters ◽  
Rate Variation ◽  
Square Cavity

A numerical study is carried out concerning mixed convection of the nanofluid in two-sided lid-driven square cavity with a pair of triangular heat sources. The upper and bottom moving walls are thermally insulated while the left and right walls are cooled at constant temperature. Two-dimensional Navier-Stokes and energy equations are solved using the finite volume discretization method with SIMPLE algorithm. The method used is validated against previous works. Two cases were considered depending on the direction of moving walls. Effects of various design parameters such as Richardson number(0.1≤Ri≤100), nanoparticle volume fraction(0≤φ≤0.05), and size(25 nm≤dp≤145 nm)and type(Cu,Al2O3,TiO2)of nanoparticles on the heat transfer rate are investigated. The results of this investigation illustrate that, by reducing the diameter of the nanoparticles andRi, the heat transfer rate increases. Moreover, it is found that by changing horizontal direction of the moving walls the heat transfer rate variation is negligible.

Natural convection heat transfer augmentation in a partially heated and partially cooled square cavity utilizing nanofluids

2009 ◽  
Vol 19 (3/4) ◽  
pp. 411-431 ◽  
Author(s):  
Manab Kumar Das ◽  
Pravin Shridhar Ohal
Keyword(s):  
Heat Transfer ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Convection Heat Transfer ◽  
Square Cavity ◽  
Content Type ◽  
Heat Transfer Augmentation ◽  
Special Cases ◽  
Simplec Algorithm ◽  
Finite Volume Approach

PurposeThe purpose of this paper is to investigate the behaviour of nanofluids numerically inside a partially heated and partially cooled square cavity to gain insight into heat transfer and flow processes induced by a nanofluid.Design/methodology/approachA model is developed to analyze the behaviour of nanofluids taking into account the solid volume fraction χ. The transport equations are solved numerically with finite volume approach using SIMPLEC algorithm.FindingsComparisons with previously published work on the basis of special cases are performed and found to be in excellent agreement. Five different relative positions of the active zones are considered.While circulation depend strongly on the total exit length. Governing parameters were 103 < Gr < 107 but due to space constraints the results for 104 < Gr <107 are presented. It is found that both the Grashof number and solid volume fraction χ affect the fluid flow and heat transfer in the cavity. CopperWater nanofluid is used with Pr = 6.2 and solid volume fraction is varied as 0, 4, 8, 12, 16 and 20 per cent. Detailed results are presented for flow pattern and heat transfer curves.Originality/valueThe present study focusses on the analysis of several parameters on the heat transfer characteristics of nanofluids within the enclosure.

Combined Mixed Convection and Radiation Heat Transfer in an Obstacle Wall Mounted Lid-driven Cavity

2016 ◽  
Vol 17 (6) ◽  
pp. 277-289 ◽  
Author(s):  
M. Moein Addini ◽  
S. A. Gandjalikhan Nassab
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Gas Flow ◽  
Radiation Heat Transfer ◽  
Simple Algorithm ◽  
Bottom Wall ◽  
Temperature Fields ◽  
Convection Flow ◽  
Driven Cavity ◽  
Laminar Mixed Convection

AbstractThis paper presents a numerical investigation for laminar mixed convection flow of a radiating gas in a lid-driven cavity with a rectangular-shaped obstacle attached on the bottom wall. The vertical walls of the square cavity are assumed to be adiabatic, while other walls of cavity and obstacle are kept at constant temperature. The fluid is treated as a gray, absorbing, emitting and scattering medium. The governing differential equations consisting the continuity, momentum and energy are solved numerically by the computational fluid dynamics techniques to obtain the velocity and temperature fields. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. Since the gas is considered as a radiating medium, besides convection and conduction, radiative heat transfer also takes place in the gas flow. For computation of the radiative term in the gas energy equation, the radiative transfer equation is solved numerically by the discrete ordinate method. The streamline and isotherm plots and the distributions of convective, radiative and total Nusselt numbers along the bottom wall of cavity are presented. The effects of Richardson number, obstacle location, radiation–conduction parameter, optical thickness and albedo coefficient on the flow and temperature distributions are carried out. Comparison between the present numerical results with those obtained by other investigators in the cases of conduction–radiation and pure convection systems shows good consistencies.

scholarly journals Premium jet cooling with two ribs over flat plate utilizing nanofluid mixed convection

2017 ◽  
Vol 21 (2) ◽  
pp. 963-976 ◽  
Author(s):  
Wael El-Maghlany ◽  
Mohamed Teamah ◽  
A.E. Kabeel ◽  
Ahmed Hanafy
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Mixed Convection ◽  
Flat Plate ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Richardson Number ◽  
Volume Fraction ◽  
Solid Volume Fraction

In this study, a numerical simulation of the thermal performance of two ribs mounted over a horizontal flat plate and cooled by Cu-water nanofluid is performed. The plate is heated and maintained at a constant temperature and cooled by mixed convection of laminar flow at a relatively low temperature. The top wall is considered as an adiabatic condition. The effects of related parameters such as Richardson number (0.01 ? Ri ? 10), the solid volume fraction (0.01 ? ? ? 0.06), the distance ratio between the two ribs (d/W = 5, 10, and 15), and the rib height ratio (b/W = 1, 2, and 3) on the ribs thermal performance are studied. The numerical simulation results indicate that the heat transfer rate is significantly affected by the distance and the rib height. The heat transfer rate is improved by increasing the nanoparticles volume fraction. The influence of the solid volume fraction with the increase of heat transfer is more noticeable for lower values of the Richardson number. The numerical results are summarized in the effect of pertinent parameters on the average Nusselt number with the assistance of both streamlines and isothermal ones. Throughout the study, the Grashof and Prandtl numbers, for pure water are kept constant at 103 and 6.2, respectively. The numerical work was displayed out using, an in-house computational fluid dynamic code written in FORTRAN, which discretizes non-dimensional forms of the governing equations using the finite volume method and solves the resulting system of equations using Gauss-Seidal method utilizing a tri diagonal matrix algorithm.

Numerical Study of Laminar Mixed Convection of a Nanofluid in a Horizontal Curved Tube with Constant Heat Flux and Mass Flow Rate

2011 ◽  
Vol 110-116 ◽  
pp. 3657-3662
Author(s):  
S. Alikhani ◽  
A. Behzadmehr ◽  
S. Mirmasoumi
Keyword(s):  
Heat Flux ◽  
Mixed Convection ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Volume Fraction ◽  
Numerical Study ◽  
Two Phase ◽  
Curved Tube ◽  
Laminar Mixed Convection

Fully developed laminar mixed convection of a nanofluid (water/Al2O3) in a horizontal curved tube is numerically investigated. Three-dimensional elliptic governing equations have been solved to show how nanoparticle concentration affects on thermal and hydrodynamic parameters while these parameters are impressed by centrifugal and buoyancy forces under constant mass flow rate and heat flux. Comparisons with previously published experimental works on horizontal curved tubes show good agreements between the results. Results which are obtained using the two – phase mixture model indicate that adding the nanoparticles causes changes in the properties of nanofluid and finally increases the temperature of the flow. Furthermore, increasing nanoparticles volume fraction at first augments the heat transfer coefficient of nanofluid and then, for higher concentration of particles, decreases this thermal parameter of nanofluid.

Numerical Study on Mixed Convection and Entropy Generation of a Nanofluid in a Lid-Driven Square Enclosure

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
R. K. Nayak ◽  
S. Bhattacharyya ◽  
I. Pop
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Numerical Study ◽  
Control Volume ◽  
Transport Equations ◽  
Bejan Number ◽  
Square Enclosure ◽  
Wide Range

A numerical investigation of mixed convection due to a copper–water nanofluid in an enclosure is presented. The mixed convection is governed by moving the upper lid of the enclosure and imposing a vertical temperature gradient. The transport equations for fluid and heat are modeled by using the Boussinesq approximation. A modified form of the control volume based SIMPLET algorithm is used for the solution of the transport equations. The fluid flow and heat transfer characteristics are studied for a wide range of Reynolds number and Grashof number so as to have the Richardson number greater or less than 1. The nanoparticle volume fraction is considered up to 20%. Heat flow patterns are analyzed through the energy flux vector. The rate of enhancement in heat transfer due to the addition of nanoparticles is analyzed. The entropy generation and Bejan number are evaluated to demonstrate the thermodynamic optimization of the mixed convection. We have obtained the enhancement rate in heat transfer and entropy generation in nanofluid for a wide range of parameter values.

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