scholarly journals Cu-Al2O3 Water Hybrid Nanofluid Transport in a Periodic Structure

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 285
Author(s):  
Aiman Alshare ◽  
Wael Al-Kouz ◽  
Waqar Khan
Keyword(s):  
Periodic Structure ◽  
Volume Fraction ◽  
Reynolds Numbers ◽  
Hybrid Nanofluid ◽  
Nanoparticle Volume Fraction ◽  
Pumping Power ◽  
Computational Investigation ◽  
Governing Equations ◽  
The Cost ◽  
Volume Method

The present work is a computational investigation of nanofluid and hybrid nanofluid transport in a periodic structure. The governing equations for this work along with the appropriate boundary conditions are solved using the finite-volume method. The simulations are carried out using five wavy amplitudes of the channel shape for a range of Reynolds numbers from 102 to103. It is found that increasing the amplitude and increasing the nanoparticle volume fraction achieve enhancement of the heat transfer at the cost of increased pumping power. Correlations for the friction factor and the Nusselt number for both fluid types are provided.

Determining the Optimum Arrangement of Micromixers in a Microchannel Filled with CuO-Water Nanofluid via Minimizing Entropy Generation

2017 ◽  
Vol 378 ◽  
pp. 39-58 ◽  
Author(s):  
Ahmad Ababaei ◽  
Mahmoud Abbaszadeh ◽  
Ali Akbar Abbasian Arani
Keyword(s):  
Boundary Conditions ◽  
Parallel Plate ◽  
Slip Velocity ◽  
Temperature Jump ◽  
Volume Fraction ◽  
Reynolds Numbers ◽  
Governing Equations ◽  
Simpler Algorithm ◽  
Optimum Arrangement ◽  
Volume Method

In this study, the flow of CuO-water nanofluid in a parallel-plate microchannel in the presence of several micromixers is examined to find optimum arrangements of the micromixers. The governing equations, which are accompanied with the slip velocity and temperature jump boundary conditions, are solved by the Finite Volume Method and SIMPLER algorithm. The study is conducted for the Reynolds numbers in the range of 10 ≤ Re ≤ 100, Knudsen numbers ranging of 0 ≤ Kn ≤ 0.1 and volume fraction of nanoparticles ranging of 0 ≤ ϕ ≤ 4%. The results show that the optimum arrangements of the micromixers belong to cases in which the heights of micromixers are smaller, the distance between them is lower, and their numbers are more.

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.

scholarly journals Entropy generation of a hybrid nanofluid on MHD mixed convection is a lid-driven cavity with partial heating having two rounded corners

2021 ◽  
Vol 321 ◽  
pp. 02004
Author(s):  
Zakaria Korei ◽  
Smail Benissaad
Keyword(s):  
Thermal Conductivity ◽  
Reynolds Number ◽  
Mixed Convection ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Object Oriented ◽  
Reynolds Numbers ◽  
Hybrid Nanofluid ◽  
Driven Cavity ◽  
Partial Heating

This research aims to investigate thermal and flow behaviors and entropy generation of magnetohydrodynamic Al2O3-Cu/water hybrid nanofluid in a lid-driven cavity having two rounded corners. A solver based on C ++ object-oriented language was developed where the finite volume was used. Parameter’s analysis is provided by varying Reynolds numbers (Re), Hartmann numbers (Ha), the volume fraction of hybrid nanofluid (ϕ), radii of the rounded corners. The findings show that reducing the radii of the rounded corners minimizes the irreversibility. Furthermore, the thermal conductivity and dynamic viscosity of hybrid nanofluid contribute to increasing the irreversibility. Finally, the entropy generation is decreased by increasing the Hartman number and increases by rising the Reynolds number.

scholarly journals Mixed Convection and Entropy Generation of an Ag-Water Nanofluid in an Inclined L-Shaped Channel

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1150 ◽  
Author(s):  
Taher Armaghani ◽  
Muneer Ismael ◽  
Ali Chamkha ◽  
Ioan Pop
Keyword(s):  
Nusselt Number ◽  
Mixed Convection ◽  
Entropy Generation ◽  
Richardson Number ◽  
Volume Fraction ◽  
Governing Equations ◽  
Nanoparticles Volume Fraction ◽  
The Mean ◽  
The Right ◽  
Volume Method

This paper investigates the mixed convection and entropy generation of an Ag-water nanofluid in an L-shaped channel fixed at an inclination angle of 30° to the horizontal axis. An isothermal heat source was positioned in the middle of the right inclined wall of the channel while the other walls were kept adiabatic. The finite volume method was used for solving the problem’s governing equations. The numerical results were obtained for a range of pertinent parameters: Reynolds number, Richardson number, aspect ratio, and the nanoparticles volume fraction. These results were Re = 50–200; Ri = 0.1, 1, 10; AR = 0.5–0.8; and φ = 0.0–0.06, respectively. The results showed that both the Reynolds and the Richardson numbers enhanced the mean Nusselt number and minimized the rate of entropy generation. It was also found that when AR. increased, the mean Nusselt number was enhanced, and the rate of entropy generation decreased. The nanoparticles volume fraction was predicted to contribute to increasing both the mean Nusselt number and the rate of entropy generation.

The Effect of Vertical Throughflow on Thermal Instability in a Porous Medium Layer Saturated by a Nanofluid: A Revised Model

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
D. A. Nield ◽  
A. V. Kuznetsov
Keyword(s):  
Boundary Condition ◽  
Porous Medium ◽  
Porous Media ◽  
Thermal Instability ◽  
Volume Fraction ◽  
Critical Rayleigh Number ◽  
Nanoparticle Volume Fraction ◽  
Governing Equations ◽  
Medium Layer ◽  
Vertical Throughflow

The model developed in our previous paper (Nield and Kuznetsov, 2011, “The Effect of Vertical Throughflow on Thermal Instability in a Porous Medium Layer Saturated by a Nanofluid,” Transp. Porous Media, 87(3), pp. 765–775) is now revised to accommodate a more realistic boundary condition on the nanoparticle volume fraction. The new boundary condition postulates zero nanoparticle flux through the boundaries. We established that in the new model, oscillatory instability is impossible. We also established that the critical Rayleigh number depends on three dimensionless parameters, and we derived these three parameters from the governing equations. We also briefly investigated the major trends.

scholarly journals Free Convection in a Triangular Cavity Filled with Hybrid-Nanofluid along with Sinusoidal Heat

2019 ◽  
Vol 4 (12) ◽  
pp. 48-52
Author(s):  
Md.Rakibul Hasan ◽  
Md. Borhan Uddin ◽  
Ahmed M. U.
Keyword(s):  
Nusselt Number ◽  
Rayleigh Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Numerical Study ◽  
Hybrid Nanofluid ◽  
Cool Temperature ◽  
Governing Equations ◽  
Uniform Cool ◽  
Generation Parameter

A numerical study on convective heat transfer of hybrid nanofluid packed in a right angled triangular cavity heated by a sinusoidal temperature maintained from lower side and subjected to a constant magnetic field have been studied in this work. The hypotenuse side of the triangular cavity has been kept in uniform cool temperature while the remaining side is insulated. The governing equations of the problem have been discretized numerically with help of finite element method. A fixed Prandtl number Pr=6.2 has been used for the numerical solution. Several values of Rayleigh number Ra=102-106 , and Hartmann number Ha=0-100 which are the non-dimensional governing parameters have been examined. The volume fraction  =0.01, 0.05, 0.1 and the heat generation parameter Q = 1 have been taken for this work. Calculate and the graph of Nusselt number corresponding to different parameters have been presented. The results show that Nusselt number has been decreasing function of nanoparticles Rayleigh number and also it is a decreasing function of Hartmann number. Obtained results has been compared with previously obtained data by other authors.

scholarly journals Effects of Surface Rotation on the Phase Change Process in a 3D Complex-Shaped Cylindrical Cavity with Ventilation Ports and Installed PCM Packed Bed System during Hybrid Nanofluid Convection

Mathematics ◽  
2021 ◽  
Vol 9 (20) ◽  
pp. 2566
Author(s):  
Lioua Kolsi ◽  
Fatih Selimefendigil ◽  
Mohamed Omri
Keyword(s):  
Phase Transition ◽  
Phase Change ◽  
Change Process ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Packed Bed ◽  
Reynolds Numbers ◽  
Hybrid Nanofluid ◽  
Surface Rotation ◽  
Phase Change Process

The combined effects of surface rotation and using binary nanoparticles on the phase change process in a 3D complex-shaped vented cavity with ventilation ports were studied during nanofluid convection. The geometry was a double T-shaped rotating vented cavity, while hybrid nanofluid contained binary Ag–MgO nano-sized particles. One of the novelties of the study wasthat a vented cavity was first used with the phase change–packed bed (PC–PB) system during nanofluid convection. The PC–PB system contained a spherical-shaped, encapsulated PCM paraffin wax. The Galerkin weighted residual finite element method was used as the solution method. The computations were carried out for varying values of the Reynolds numbers (100 ≤ Re ≤ 500),rotational Reynolds numbers (100 ≤ Rew ≤ 500), size of the ports (0.1L1 ≤ di ≤ 0.5L1), length of the PC–PB system (0.4L1 ≤ L0 ≤ L1), and location of the PC–PB (0 ≤ yp ≤ 0.25H). In the heat transfer fluid, the nanoparticle solid volume fraction amount was taken between 0 and 0.02%. When the fluid stream (Re) and surface rotational speed increased, the phase change process became fast. Effects of surface rotation became effective for lower values of Re while at Re = 100 and Re = 500; full phase transition time (tp) was reduced by about 39.8% and 24.5%. The port size and nanoparticle addition in the base fluid had positive impacts on the phase transition, while 34.8% reduction in tp was obtained at the largest port size, though this amount was only 9.5%, with the highest nanoparticle volume fraction. The length and vertical location of the PC–PB system have impacts on the phase transition dynamics. The reduction and increment amount in the value of tp with varying location and length of the PC–PB zone became 20% and 58%. As convection in cavities with ventilation ports are relevant in many thermal energy systems, the outcomes of this study will be helpful for the initial design and optimization of many PCM-embedded systems encountered in solar power, thermal management, refrigeration, and many other systems.

scholarly journals Natural Convection over Two Superellipse Shapes with a Porous Cavity Populated by Nanofluid

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6952
Author(s):  
Noura Alsedais
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Governing Equations ◽  
Porous Layers ◽  
Porous Cavity ◽  
The Mean ◽  
Volume Method

The influences of superellipse shapes on natural convection in a horizontally subdivided non-Darcy porous cavity populated by Cu-water nanofluid are inspected in this paper. The impacts of the inner geometries (n = 0.5,1,1.5,4) Rayleigh number (103 ≤ Ra ≤ 106), Darcy number (10−5 ≤ Da ≤ 10−2), porosity (0.2 ≤ ϵ ≤ 0.8), and solid volume fraction (0.01 ≤ ∅ ≤ 0.05) on nanofluid heat transport and streamlines were examined. The hot superellipse shapes were placed in the cavity’s bottom and top, while the adiabatic boundaries on the flat walls of the cavity were considered. The governing equations were numerically solved using the finite volume method (FVM). It was found that the movement of the nanofluid upsurged as Ra boosted. The temperature distributions in the cavity’s core had an inverse relationship with increasing Rayleigh number. An extra porous resistance at lower Darcy numbers limited the nanofluid’s movement within the porous layers. The mean Nusselt number decreased as the porous resistance increased (Da ≤ 10−4). The flow and temperature were strongly affected as the shape of the inner superellipse grew larger.

A Study on Hydromagnetic Pulsating Flow of a Nanofluid in a Porous Channel With Thermal Radiation

2016 ◽  
Vol 33 (2) ◽  
pp. 213-224 ◽  
Author(s):  
A. Vijayalakshmi ◽  
S. Srinivas
Keyword(s):  
Heat Transfer ◽  
Titanium Dioxide ◽  
Thermal Radiation ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Porous Channel ◽  
Nanoparticle Volume Fraction ◽  
Governing Equations ◽  
Nanofluid Flow

AbstractThe present study investigates the hydromagnetic pulsating nanofluid flow in a porous channel with thermal radiation. In this work, we considered water as the base fluid and silver (Ag), copper (Cu), alumina (Al2O3) and titanium dioxide (TiO2) as nanoparticles. The Maxwell-Garnetts and Brinkman models are used to evaluate the effective thermal conductivity and viscosity of the nanofluid. The governing equations are solved analytically and the influence of various parameters on velocity, temperature and heat transfer rate has been discussed through graphical results. From the results, it is found that the rate of heat transfer enhances with an increase of nanoparticle volume fraction. Further, the heat transfer rate is higher for silver nanoparticles as compared with copper, alumina and titanium dioxide.

Thermal and Hydraulic Performance of Counterflow Microchannel Heat Exchangers With and Without Nanofluids

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Hamid Reza Seyf ◽  
Shahabeddin Keshavarz Mohammadian
Keyword(s):  
Reynolds Number ◽  
Brownian Motion ◽  
Performance Index ◽  
Volume Fraction ◽  
Reynolds Numbers ◽  
Hydraulic Performance ◽  
Working Fluid ◽  
Pumping Power ◽  
Mean Diameter ◽  
And Performance

Abstract This paper analyzes the thermal and hydraulic performance of a counterflow microchannel heat exchanger (CFMCHE) with and without nanofluid as working fluid. A 3D conjugate heat transfer simulation is carried out using a finite volume approach to evaluate the effects of inlet Reynolds number, Brownian motion, and volume fraction of nanoparticles on the pumping power, effectiveness, and performance index of CFMCHE. The accuracy of the code has been verified by comparing the results with those available in the literature. A single phase approach is used for the nanofluid modeling. The base fluid used in the analyses as a basis for comparison was pure water. Two types of nanofluids, namely, water-Al2O3 with a mean diameter of 47 nm and water-CuO with a mean diameter of 29 nm, each one with three different volume fractions, are utilized. In addition, two temperature dependent models for the thermal conductivity and viscosity of nanofluids that account for the fundamental role of Brownian motion are used. Calculated results demonstrate that the effectiveness and performance index of CFMCHE decrease with increasing Reynolds number. Moreover, it is observed that the relative enhancements in the pumping power become more prominent for higher values of Reynolds numbers. It was also found that the performance index and pumping power are not sensitive to volume fraction at higher and lower Reynolds numbers, respectively.

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