scholarly journals Mixed Convection Heat Transfer for Nanofluids in a Lid-Driven Shallow Rectangular Cavity Uniformly Heated and Cooled from the Vertical Sides: The Cooperative Case

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
Hassan Elharfi ◽  
Mohamed Naïmi ◽  
Mohamed Lamsaadi ◽  
Abdelghani Raji ◽  
Mohammed Hasnaoui
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Volume Fraction ◽  
Pure Water ◽  
Solid Volume Fraction ◽  
Rectangular Cavity ◽  
Temperature Fields ◽  
Vertical Side ◽  
Simpler Algorithm ◽  
Wide Range

A study of mixed convection, in a shallow lid-driven rectangular cavity filled with water-based nanofluids and subjected to uniform heat flux along the vertical side walls, has been performed numerically by solving the full governing equations via the finite volume method and the SIMPLER algorithm. In the limit of a shallow enclosure, these equations have been considerably reduced by using the parallel flow approximation. Solutions, for the flow and temperature fields, and the heat transfer rate, have been obtained as functions of the governing parameters, namely, the Reynolds (Re) and the Richardson (Ri) numbers and the solid volume fraction of nanoparticles (Φ). A good agreement has been obtained between the results of the two approaches for a wide range of the governing parameters. Moreover, it has been found that the addition of Cu-nanoparticles, into the pure water, leads to an enhancement or a degradation of heat transfer depending on the values of Re and Ri.

scholarly journals Natural convective flow in circular and arc cavities filled with water-cu nanofluid: a comparative study

2018 ◽  
Vol 15 (1) ◽  
pp. 37-52 ◽  
Author(s):  
Khandker Farid Uddin Ahmed ◽  
Rehena Nasrin ◽  
Md. Elias
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Pure Water ◽  
Solid Volume Fraction ◽  
Viscous Force ◽  
Wide Range ◽  
Prandtl Numbers

The fluid flow and heat transfer mechanism on steady state solutions obtained in circular and arc-square enclosures filled with water/Cu nanofluid as well as base fluid has been investigated numerically by Galerkin's weighted residual finite element procedure. The left and right boundaries of the cavities are, respectively, heated and cooled at constant temperatures, while their horizontal walls are adiabatic. Effects of buoyancy force (Rayleigh number) and viscous force (Prandtl number) with a wide range of Ra (103 - 106) and Pr (4.2 - 6.2) on heat transfer phenomenon inside cavities are observed. The fluid flow and temperature gradient are shown by streamlines and isotherms patterns. From the investigation, it is reported that the Rayleigh and Prandtl numbers are playing significant role in heat transfer rate. The variation in heat transfer is calculated in terms of average Nusselt number. Heat transfer rate is found to be higher for water/Cu nanofluid with 2% solid volume fraction than pure water. About 2.7% higher heat transfer rate is obtained for circular cavity than that of arc cavity using water/Cu nanofluid at Ra = 104 and Pr = 5.8.

Turbulent Nanofluid Flow Analysis Passing a Shell and Tube Thermal Exchanger with Kays-Crawford Model

2021 ◽  
Vol 10 (4) ◽  
pp. 518-537
Author(s):  
R. Nasrin ◽  
S. A. Sweety ◽  
I. Zahan
Keyword(s):  
Heat Transfer ◽  
Volume Fraction ◽  
Pure Water ◽  
Fluid Velocity ◽  
Solid Volume Fraction ◽  
Heat Transfer Analysis ◽  
Inlet Temperature ◽  
Industrial Sectors ◽  
Shell And Tube ◽  
Thermal Exchanger

Temperature dissipation in a proficient mode has turned into a crucial challenge in industrial sectors because of worldwide energy crisis. In heat transfer analysis, shell and tube thermal exchangers is one of the mostly used strategies to control competent heat transfer in industrial progression applications. In this research, a numerical analysis of turbulent flow has been conceded in a shell and tube thermal exchanger using Kays-Crawford model to investigate the thermal performance of pure water and different concentrated water-MWCNT nanofluid. By means of finite element method the Reynold-Averaged Navier-Stokes (RANS) and heat transport equations along with suitable edge conditions have been worked out numerically. The implications of velocity, solid concentration, and temperature of water-MWCNT nanofluid on the fluid flow formation and heat transfer scheme have been inspected thoroughly. The numerical results indicate that the variation of nanoparticles solid volume fraction, inflow fluid velocity and inlet temperature mannerism considerably revolutionize in the flow and thermal completions. It is perceived that using 3% concentrated water-MWCNT nanofluid, higher rate of heat transfer 12.24% is achieved compared that of water and therefore to enhance the efficiency of this heat exchanger. Furthermore, a new correlation has been developed among obtained values of thermal diffusion rate, Reynolds number and volume concentration of nanoparticle and found very good correlation coefficient among the values.

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.

Flow and heat transfer of couple stress nanofluid sandwiched between viscous fluids

2019 ◽  
Vol 29 (11) ◽  
pp. 4262-4276 ◽  
Author(s):  
C. Jawali Umavathi ◽  
Mikhail Sheremet
Keyword(s):  
Heat Transfer ◽  
Couple Stress ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Viscous Fluids ◽  
Temperature Fields ◽  
Content Type ◽  
Stress Parameter ◽  
Transfer Behavior ◽  
Velocity And Temperature Fields

Purpose The purpose of this study is a numerical analysis of steady-state heat transfer behavior of couple-stress nanofluid sandwiched between viscous fluids. It should be noted that this research deals with the development of a cooling system for the electronic devices. Design/methodology/approach Stokes model is used to define the couple-stress fluid and the single-phase nanofluid model is used to define the nanofluid transport processes. The fluids in all regions are assumed to be incompressible, immiscible and the transport properties in all the three layers are assumed to be constant. The governing coupled linear ordinary differential equations are made dimensionless by using appropriate fundamental quantities. The exact solutions obtained for the velocity and temperature fields are evaluated numerically for various model parameters. Findings The results are demonstrated using different types of nanoparticles such as copper, silver, silicon oxide (SiO2), titanium oxide (TiO2) and diamond. The investigations are carried out using copper–water nanofluid for different values of couple-stress parameter a with a range of 0 = a = 12, solid volume fraction ϕ with a range of 0.0 ≤ ϕ ≤ 0.05, Eckert number Ec with a range of 0.001 ≤ Ec ≤ 6 and Prandtl number Pr with a range of 0.001 ≤ Pr ≤ 6. It was found that the Nusselt number increases by increasing the couple stress parameter, Eckert number and Prandtl number and it decreases with a growth of the solid volume fraction parameter. It was also observed that using SiO2–water nanofluid, the optimal Nusselt number is obtained. Further, using copper, silver, diamond and TiO2, nanoparticles and water as a base fluid does not show any significant changes in the rate of heat transfer. The couple-stress parameter enhances the velocity and temperature fields whereas the solid volume fraction suppresses the flow field for both Newtonian and couple-stress fluid. Originality/value The originality of this work is to analyze the heat transfer behavior of couple-stress nanofluid sandwiched between viscous fluids. The results would benefit scientists and engineers to become familiar with the analysis of convective heat transfer and flow structures in nanofluids and the way to predict the heat transfer rate in advanced technical systems, in industrial sectors including transportation, power generation, chemical sectors, electronics, etc.

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.

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 Mixed convection inside nanofluid filled rectangular enclosures with moving bottom wall

2011 ◽  
Vol 15 (3) ◽  
pp. 889-903 ◽  
Author(s):  
Mostafa Mahmoodi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Richardson Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Flow And Heat Transfer ◽  
Simpler Algorithm ◽  
Horizontal Wall

The mixed convection fluid flow and heat transfer in lid-driven rectangular enclosures filled with the Al2O3-water nanofluid is investigated numerically. The left and the right vertical walls as well as the top horizontal wall of the enclosure are maintained at a constant cold temperature Tc. The bottom horizontal wall of the enclosure, which moves from left to right, is kept at a constant hot temperature Th, with Th>Tc. The governing equations written in terms of the primitive variables are solved using the finite volume method and the SIMPLER algorithm. Using the developed code, a parametric study is performed and the effects of the Richardson number, the aspect ratio of the enclosure and the volume fraction of the nanoparticles on the fluid flow and heat transfer inside the enclosure are investigated. The results show that at low Richardson numbers, a primary counterclockwise vortex is formed inside the enclosure. More over it is found that for the range of the Richardson number considered, 10-1-101, the average Nusselt number of the hot wall, increases with increasing the volume fraction of the nanoparticles. Also it is observed that the average Nusselt number of the hot wall of tall enclosures is more that to that of the shallow enclosures.

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.

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 Applied Mathematical Modelling and Heat Transport Investigation in Hybrid Nanofluids under the Impact of Thermal Radiation: Numerical Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Umar Khan ◽  
Basharat Ullah ◽  
Wahid Khan ◽  
Adnan ◽  
Ilyas Khan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Differential Equations ◽  
Mixed Convection ◽  
Dynamic Viscosity ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Temperature Fields ◽  
Convection Boundary Layer ◽  
Heat Transmission ◽  
The Impact

Nanofluids are solid-liquid mixtures that have a dispersion of nanometer-sized particles in conventional base fluids. The flow and heat transmission in an unstable mixed convection boundary layer are affected by the thermal conductivity and dynamic viscosity uncertainty of a nanofluid over a stretching vertical surface. There is time-dependent stretching velocity and surface temperature instability in both the flow and temperature fields. It is possible to scale the governing partial differential equations and then solve them using ordinary differential equations. Cu and Al2O3 nanofluids based on water are among the possibilities being investigated. An extensive discussion has been done on relevant parameters such as the unsteadiness parameter and the mixed convection parameter's effect on solid volume fraction of nanoparticles. In addition, alternative nanofluid models based on distinct thermal conductivity and dynamic viscosity formulas are examined for their flow and heat transmission properties. On the basis of the comparison, it is concluded that the results are spot on for steady state flow.

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