Numerical Analysis of Magnetic Field and Heat Transfer of a Reciprocating Magnetocaloric Regenerator Using a Halbach Magnet Array

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Tunahan Akış ◽  
Abdullatif Hamad ◽  
Mehmet Akif Ezan ◽  
Erim Yanık ◽  
Ahmet Yılancı ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Pressure Difference ◽  
Thermal Analyses ◽  
Temperature Drop ◽  
Reynolds Numbers ◽  
Heat Transfer Fluid ◽  
Ansys Fluent ◽  
Fluent Software ◽  
The Magnetic Field

Abstract In this study, a numerical model of a reciprocating magnetocaloric regenerator using a Halbach magnet array is developed in ansys-fluent software. The model consists of three components, namely, (i) the Halbach magnet array, (ii) the magnetocaloric material (MCM), and (iii) the heat transfer fluid. A two-dimensional (2D) domain is studied due to the axisymmetric geometry of the physical model. A pressure difference is defined between the inlet and outlet sections of the fluid domain to maintain a reciprocating fluid flow. In the proposed computational scheme, a segregated approach is followed to consider the spatial distribution of the magnetic field in the thermal analyses. Therefore, a 2D magnetic field within the MCM is computed using an analytical approach at first, and its results are integrated into ansys-fluent with a user-defined function (UDF). Hydrodynamic and heat transfer characteristics of the proposed regenerator model are evaluated under various Reynolds numbers and cycle durations. Moreover, the temperature drop at the cold side of the regenerator is represented in terms of the pressure difference, flow duration, and the diameter of Gadolinium (Gd) as the MCM. For the current geometrical configurations, it is observed that the magnetic field varies from 0.4 T to 1 T within Gd. The highest temperature spans are measured as 8.4 K, 7.5 K, and 7.2 K numerically for the cycle durations of 1.2 s, 2.2 s, and 4.2 s, respectively.

scholarly journals Теплообмен при смешанной конвекции расплава соли в присутствии магнитных полей

2019 ◽  
Vol 45 (10) ◽  
pp. 27
Author(s):  
И.А. Беляев ◽  
Д.А. Бирюков ◽  
А.В. Котляр ◽  
Е.А. Белавина ◽  
П.А. Сардов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Temperature Fluctuations ◽  
Reynolds Numbers ◽  
Transverse Magnetic ◽  
Statistical Characteristics ◽  
Transfer Coefficients ◽  
Gravitational Flow ◽  
Heat Transfer Coefficients ◽  
The Magnetic Field

The results of an experimental study of the salt melt downflow in a uniformly heated pipe under the influence of a strong transverse magnetic field are presented. The changes of heat transfer coefficients and statistical characteristics of temperature fluctuations under the influence of the magnetic field are investigated. The peculiarities of the transition of the viscous-gravitational flow in the viscous-inertial-gravitational flow at Reynolds numbers (Re=3000-5000) under the influence of the magnetic field (Ha=17) were studied.

scholarly journals Unsteady squeezing flow of Cu-Al2O3/water hybrid nanofluid in a horizontal channel with magnetic field

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Najiyah Safwa Khashi’ie ◽  
Iskandar Waini ◽  
Norihan Md Arifin ◽  
Ioan Pop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Fluid ◽  
Lower Plate ◽  
Squeezing Flow ◽  
Hybrid Nanofluid ◽  
Parallel Plates ◽  
User Friendly ◽  
Wall Mass ◽  
The Magnetic Field

AbstractThe proficiency of hybrid nanofluid from Cu-Al2O3/water formation as the heat transfer coolant is numerically analyzed using the powerful and user-friendly interface bvp4c in the Matlab software. For that purpose, the Cu-Al2O3/water nanofluid flow between two parallel plates is examined where the lower plate can be deformed while the upper plate moves towards/away from the lower plate. Other considerable factors are the wall mass suction/injection and the magnetic field that applied on the lower plate. The reduced ordinary (similarity) differential equations are solved using the bvp4c application. The validation of this novel model is conducted by comparing a few of numerical values for the reduced case of viscous fluid. The results imply the potency of this heat transfer fluid which can enhance the heat transfer performance for both upper and lower plates approximately by 7.10% and 4.11%, respectively. An increase of squeezing parameter deteriorates the heat transfer coefficient by 4.28% (upper) and 5.35% (lower), accordingly. The rise of suction strength inflates the heat transfer at the lower plate while the presence of the magnetic field shows a reverse result.

Thermodynamic Analysis of Magnetic Refrigerators

2004 ◽  
Author(s):  
Muhammad M. Rahman ◽  
Luis Rosario
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Exchangers ◽  
Room Temperature ◽  
Fluid Flows ◽  
Heat Transfer Fluid ◽  
Cooling Power ◽  
Refrigeration Cycle ◽  
Heating Effects ◽  
The Magnetic Field

An analysis of a magnetic refrigeration cycle was carried out. The system consists of heat exchangers and beds of magnetic materials. The analysis considered that the system operates near room temperature in a magnetic field between 1 and 5 T and uses 3 kg of gadolinium (Gd) spheres packed in two magnetocaloric beds. The heat transfer fluid is water. The beds are periodically magnetized and demagnetized and the fluid flows are arranged to meet the cycle requirements. Sensitivity analysis has been performed. Cooling power, magnetic field, and temperature span trends are simulated. The cooling and heating effects were estimated based on the magnetocaloric effect of gadolinium. Findings indicate that the higher the magnetic field is the higher the cooling power with the same temperature span. It was also observed that the cooling power decreases with the increase in the temperature span for various magnetic fields. COP vs. temperature span was also considered. The trend indicates that COPactual/ COPCarnot decreases with an increase in the temperature span. These trends agreed with those shown by experimental data.

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

scholarly journals Effect of Magnetic Field on the Forced Convective Heat Transfer of Water–Ethylene Glycol-Based Fe3O4 and Fe3O4–MWCNT Nanofluids

2021 ◽  
Vol 11 (10) ◽  
pp. 4683
Author(s):  
Areum Lee ◽  
Chinnasamy Veerakumar ◽  
Honghyun Cho
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Field Strength ◽  
Ethylene Glycol ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Hybrid Nanofluid ◽  
Forced Convective Heat Transfer ◽  
The Magnetic Field

This paper discusses the forced convective heat transfer characteristics of water–ethylene glycol (EG)-based Fe3O4 nanofluid and Fe3O4–MWCNT hybrid nanofluid under the effect of a magnetic field. The results indicated that the convective heat transfer coefficient of magnetic nanofluids increased with an increase in the strength of the magnetic field. When the magnetic field strength was varied from 0 to 750 G, the maximum convective heat transfer coefficients were observed for the 0.2 wt% Fe3O4 and 0.1 wt% Fe3O4–MWNCT nanofluids, and the improvements were approximately 2.78% and 3.23%, respectively. The average pressure drops for 0.2 wt% Fe3O4 and 0.2 wt% Fe3O4–MWNCT nanofluids increased by about 4.73% and 5.23%, respectively. Owing to the extensive aggregation of nanoparticles by the external magnetic field, the heat transfer coefficient of the 0.1 wt% Fe3O4–MWNCT hybrid nanofluid was 5% higher than that of the 0.2 wt% Fe3O4 nanofluid. Therefore, the convective heat transfer can be enhanced by the dispersion stability of the nanoparticles and optimization of the magnetic field strength.

Effects of uniform or non-uniform heating at bottom wall on MHD mixed convection in a porous cavity saturated by nanofluid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Subramanian Muthukumar ◽  
Selvaraj Sureshkumar ◽  
Arthanari Malleswaran ◽  
Murugan Muthtamilselvan ◽  
Eswari Prem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Bottom Wall ◽  
Uniform Heating ◽  
The Magnetic Field

Abstract A numerical investigation on the effects of uniform and non-uniform heating of bottom wall on mixed convective heat transfer in a square porous chamber filled with nanofluid in the appearance of magnetic field is carried out. Uniform or sinusoidal heat source is fixed at the bottom wall. The top wall moves in either positive or negative direction with a constant cold temperature. The vertical sidewalls are thermally insulated. The finite volume approach based on SIMPLE algorithm is followed for solving the governing equations. The different parameters connected with this study are Richardson number (0.01 ≤ Ri ≤ 100), Darcy number (10−4 ≤ Da ≤ 10−1), Hartmann number (0 ≤ Ha ≤ 70), and the solid volume fraction (0.00 ≤ χ ≤ 0.06). The results are presented graphically in the form of isotherms, streamlines, mid-plane velocities, and Nusselt numbers for the various combinations of the considered parameters. It is observed that the overall heat transfer rate is low at Ri = 100 in the positive direction of lid movement, whereas it is low at Ri = 1 in the negative direction. The average Nusselt number is lowered on growing Hartmann number for all considered moving directions of top wall with non-uniform heating. The low permeability, Da = 10−4 keeps the flow pattern same dominating the magnetic field, whereas magnetic field strongly affects the flow pattern dominating the high Darcy number Da = 10−1. The heat transfer rate increases on enhancing the solid volume fraction regardless of the magnetic field.

Numerical Simulation of High-Aspect-Ratio Micro-Hole Electroforming with External Magnetic Field

2010 ◽  
Vol 42 ◽  
pp. 13-16
Author(s):  
Wei Li ◽  
Ping Mei Ming ◽  
Wu Ji Jiang ◽  
Yin Ding Lv
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Flow State ◽  
Cathode Electrode ◽  
Micro Hole ◽  
Fluent Software ◽  
The Magnetic Field ◽  
Enhance Mass

In this paper, the influences of applied magnetic field on flow state during electroforming of the high-aspect-ratio (HAR) blind micro-hole were numerically analyzed using the Fluent software. The results showed that, when microelectroforming of nickel without external agitation, three vortexes could form due to the magnetohydrodynamic (MHD) effect within the HAR micro-hole with magnetic field in parallel to cathode-electrode surface, and the flow rate in the micro-hole increased with the increase of the magnetic field and current density. The MHD effect helped to enhance mass transfer during the microelectroforming of HAR microstructures.

scholarly journals Heat Transfer to MHD Oscillatory Viscoelastic Flow in a Channel Filled with Porous Medium

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Rita Choudhury ◽  
Utpal Jyoti Das
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Porous Medium ◽  
Radiative Heat ◽  
Saturated Porous Medium ◽  
Transverse Magnetic ◽  
Viscoelastic Flow ◽  
Viscoelastic Parameter ◽  
Flow Parameters ◽  
The Magnetic Field

The combined effect of a transverse magnetic field and radiative heat transfer on unsteady flow of a conducting optically thin viscoelastic fluid through a channel filled with saturated porous medium and nonuniform walls temperature has been discussed. It is assumed that the fluid has small electrical conductivity and the electromagnetic force produced is very small. Closed-form analytical solutions are constructed for the problem. The effects of the radiation and the magnetic field parameters on velocity profile and shear stress for different values of the viscoelastic parameter with the combination of the other flow parameters are illustrated graphically, and physical aspects of the problem are discussed.

scholarly journals Research on convective heat transfer characteristics of Fe3O4magnetic nanofluids under vertical magnetic field

2021 ◽  
pp. 151-151
Author(s):  
Ruihao Zhang ◽  
Sixian Wang ◽  
Shan Qing ◽  
Zhumei Luo ◽  
Zhang Xiaohui
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Reynolds Number ◽  
Field Strength ◽  
Convective Heat Transfer ◽  
Magnetic Field Strength ◽  
Convective Heat ◽  
Heat Transfer Characteristics ◽  
Magnetic Nanofluids ◽  
The Magnetic Field

This paper focuses on the convective heat transfer characteristics of Fe3O4 /Water magnetic nanofluids under laminar and turbulent conditions. After verifying the accuracy of the experimental apparatus, the effects of magnetic field strength, concentration, Reynolds number and temperature on the convective heat transfer coefficient have been studied. The convective heat transfer characteristics of nanofluids under laminar and turbulent flow conditions were studied in depth, and the influence of each factor on the heat transfer coefficient was analyzed by orthogonal experimental design method. Under the laminar flow conditions, the convective heat transfer of magnetic nanofluids performed best when the Reynolds number was 2000, the magnetic field strength was 600, the temperature was 30? and the concentration was 2%. And the convective heat transfer coefficient (h) increased by 3.96% than the distilled water in the same conditions. In turbulent state, the convective heat transfer of magnetic nanofluids performed the best when the Re was 6000, the magnetic field strength was 600, the temperature was 40? and the concentration was 2%. The h increased by 11.31% than the distilled water in the same Reynolds number and the magnetic field strength conditions.

Magnetohydrodynamic effects on flow structures and heat transfer over two cylinders wrapped with a porous layer in side

2016 ◽  
Vol 26 (5) ◽  
pp. 1416-1432 ◽  
Author(s):  
Saman Rashidi ◽  
Javad Abolfazli Esfahani ◽  
Mohammad Sadegh Valipour ◽  
Masoud Bovand ◽  
Ioan Pop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Flow Field ◽  
Porous Layer ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Circular Cylinders ◽  
Flow Structures ◽  
Content Type ◽  
The Magnetic Field

Purpose – The analysis of the flow field and heat transfer around a tube row or tube banks wrapped with porous layer have many related engineering applications. Examples include the reactor safety analysis, combustion, compact heat exchangers, solar power collectors, high-performance insulation for buildings and many another applications. The purpose of this paper is to perform a numerical study on flows passing through two circular cylinders in side-by-side arrangement wrapped with a porous layer under the influence of a magnetic field. The authors focus the attention to the effects of magnetic field, Darcy number and pitch ratio on the mechanism of convection heat transfer and flow structures. Design/methodology/approach – The Darcy-Brinkman-Forchheimer model for simulating the flow in porous medium along with the Maxwell equations for providing the coupling between the flow field and the magnetic field have been used. Equations with the relevant boundary conditions are numerically solved using a finite volume approach. In this study, Stuart and Darcy numbers are varied within the range of 0 < N < 3 and 1e-6 < Da < 1e-2, respectively, and Reynolds and Prandtl numbers are equal to Re=100 and Pr=0.71, respectively. Findings – The results show that the drag coefficient decreases for N < 0.6 and increases for N > 0.6. Also, the effect of magnetic field is negligible in the gap between two cylinders because the magnetic field for two cylinders counteracts each other in these regions. Originality/value – To the authors knowledge, in the open literature, flow passing over two circular cylinders in side-by-side arrangement wrapped with a porous layer has been rarely investigated especially under the influence of a magnetic field.

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