Investigating the effect of alumina nanoparticles on heat transfer and entropy generation inside a square enclosure equipped with two inclined blades under magnetic field

2019 ◽  
Vol 152 ◽  
pp. 312-328 ◽  
Author(s):  
Abdullah A.A.A. Al-Rashed
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Entropy Generation ◽  
Alumina Nanoparticles ◽  
Square Enclosure

scholarly journals Natural Convection and Entropy Generation of MgO/Water Nanofluids in the Enclosure under a Magnetic Field and Radiation Effects

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1277
Author(s):  
Yacine Khetib ◽  
Ahmad Aziz Alahmadi ◽  
Ali Alzaed ◽  
Ahamd Tahmasebi ◽  
Mohsen Sharifpur ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Entropy Generation ◽  
Radiation Effects ◽  
Volume Fraction ◽  
Numerical Study ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
The Other ◽  
Square Enclosure

The authors of the present paper sought to conduct a numerical study on the convection heat transfer, along with the radiation and entropy generation (EGE) of a nanofluids (NFs) in a two and three-dimensional square enclosure, by using the FVM. The enclosure contained a high-temperature blade in the form of a vertical elliptical quadrant in the lower corner of the enclosure. The right edge of the enclosure was kept at low temperature, while the other edges were insulated. The enclosure was subjected to a magnetic field (MGF) and could be adjusted to different angles. In this research, two laboratory relationships dependent on temperature and volume fraction were used to simulate thermal conductivity and viscosity. The variables of this problem were Ra, Ha, RAP, nanoparticle (NP) volume fraction, blade aspect ratio, enclosure angles, and MGF. Evaluating the effects of these variables on heat transfer rate (HTR), EGE, and Be revealed that increasing the Ra and reducing the Ha could increase the HTR and EGE. On the other hand, adding radiation HTR to the enclosure increased the overall HTR. Moreover, an augmentation of the volume fraction of magnesium oxide NPs led to an increased amount of HTR and EGE. Furthermore, any changes to the MGF and the enclosure angle imposed various effects on the HTR. The results indicated that an augmentation of the size of the blade increased and then decreased the HTR and the generated entropy. Finally, increasing the blade always increased the Be.

Effect of magnetic field-dependent thermal conductivity on natural convection of magnetic nanofluid inside a square enclosure

2019 ◽  
Vol 29 (4) ◽  
pp. 1466-1489 ◽  
Author(s):  
Mohammadhossein Hajiyan ◽  
Shohel Mahmud ◽  
Mohammad Biglarbegian ◽  
Hussein A. Abdullah ◽  
A. Chamkha
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Magnetic Nanofluid ◽  
Content Type ◽  
Square Enclosure ◽  
Field Dependent

Purpose The purpose of this paper is to investigate the convective heat transfer of magnetic nanofluid (MNF) inside a square enclosure under uniform magnetic fields considering nonlinearity of magnetic field-dependent thermal conductivity. Design/methodology/approach The properties of the MNF (Fe3O4+kerosene) were described by polynomial functions of magnetic field-dependent thermal conductivity. The effect of the transverse magnetic field (0 < H < 105), Hartmann Number (0 < Ha < 60), Rayleigh number (10 <Ra <105) and the solid volume fraction (0 < φ < 4.7%) on the heat transfer performance inside the enclosed space was examined. Continuity, momentum and energy equations were solved using the finite element method. Findings The results show that the Nusselt number increases when the Rayleigh number increases. In contrast, the convective heat transfer rate decreases when the Hartmann number increases due to the strong magnetic field which suppresses the buoyancy force. Also, a significant improvement in the heat transfer rate is observed when the magnetic field is applied and φ = 4.7% (I = 11.90%, I = 16.73%, I = 10.07% and I = 12.70%). Research limitations/implications The present numerical study was carried out for a steady, laminar and two-dimensional flow inside the square enclosure. Also, properties of the MNF are assumed to be constant (except thermal conductivity) under magnetic field. Practical implications The results can be used in thermal storage and cooling of electronic devices such as lithium-ion batteries during charging and discharging processes. Originality/value The accuracy of results and heat transfer enhancement having magnetic field-field-dependent thermal conductivity are noticeable. The results can be used for different applications to improve the heat transfer rate and enhance the efficiency of a system.

Numerical Thermal Analysis of a Hot Non-circular Rotating Cylinder in the Presence of a Magnetic Field

2021 ◽  
Author(s):  
Hojjat Khozeymeh-Nezhad ◽  
Yaser Basati ◽  
Hamid Niazmand
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Circular Cylinder ◽  
Transfer Rate ◽  
Elliptic Cylinder ◽  
Optimal Location ◽  
Elliptical Cylinder ◽  
Square Enclosure ◽  
Cylinder Rotation

Abstract In the present paper for the first time, a Lattice Boltzmann Simulation is performed to analyze the simultaneous effects of a hot rotating elliptic cylinder and the magnetic field on the mixed convection flow in a square enclosure. Complicated flow patterns and isotherms plots are found and analyzed in the concentric annulus between the internal elliptic cylinder and the outer square enclosure. Results indicate that increasing the Reynolds number, instantaneous averaged Nusselt number of the enclosure and its oscillation amplitude increase, while decrease with increasing the Hartmann number especially at its lower values. Furthermore, response surface method is adopted to find the optimal location of the elliptic cylinder. Response surface optimization results reveal that the average Nusselt number shows a decreasing-increasing trend with increasing both non-dimensional parameters of cylinder center (Xc,Yc) Finally, the optimal location of the elliptic cylinder for the maximum heat transfer rate is obtained as Xc=0.65 and Yc=0.35. Moreover, a comparative study is performed to evaluate the heat transfer effects of the elliptical cylinder rotation as compared to circular cylinder. It was found that the elliptical cylinder rotation has a significant effect on the heat transfer enhancement, especially at high values of Re and Ha. As an example, the heat transfer rate for the elliptical cylinder at Re=200 is increased by 13 % and 34% as compared to the circular cylinder at Ha=50 and 100, respectively.

Free convection/radiation and entropy generation analyses for nanofluid of inclined square enclosure with uniform magnetic field

2020 ◽  
Vol 141 (1) ◽  
pp. 635-648 ◽  
Author(s):  
Yuanzhou Zheng ◽  
Somaye Yaghoubi ◽  
Amin Dezfulizadeh ◽  
Saeed Aghakhani ◽  
Arash Karimipour ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Free Convection ◽  
Entropy Generation ◽  
Uniform Magnetic Field ◽  
Square Enclosure
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