Two-phase analysis of heat transfer and entropy generation of water-based magnetite nanofluid flow in a circular microtube with twisted porous blocks under a uniform magnetic field

2021 ◽  
Vol 384 ◽  
pp. 522-541
Author(s):  
Muhammad Ibrahim ◽  
Tareq Saeed ◽  
Firooz Riahi Bani ◽  
Shahab Naghdi Sedeh ◽  
Yu-Ming Chu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Phase Analysis ◽  
Entropy Generation ◽  
Uniform Magnetic Field ◽  
Nanofluid Flow ◽  
Two Phase ◽  
Water Based ◽  
Porous Blocks

MHD natural convection in a square porous cavity filled with a water-based magnetic fluid in the presence of geothermal viscosity

2018 ◽  
Vol 28 (9) ◽  
pp. 2111-2131 ◽  
Author(s):  
Mikhail A. Sheremet ◽  
Marina S. Astanina ◽  
Ioan Pop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Magnetic Fluid ◽  
Convective Flow ◽  
Uniform Magnetic Field ◽  
Vertical Wall ◽  
Content Type ◽  
Porous Cavity ◽  
Water Based

Purpose The purpose of this paper is a numerical analysis of natural convection in a square porous cavity filled with a water-based magnetic fluid of geothermal viscosity under the effect of inclined uniform magnetic field. Design/methodology/approach The domain of interest includes the square porous cavity filled with a water-based magnetic fluid (W40). Horizontal walls are supposed to be adiabatic, while right vertical wall is kept at constant low temperature and left vertical wall is kept at constant high temperature. An inclined uniform magnetic field affects the fluid flow and heat transfer inside the cavity. The viscosity of the working fluid is proportional to the linearly decreasing function of depth (vertical coordinate) and inversely proportional to the linear function of temperature. It is assumed in the analysis that the flow is laminar. The fluid is Newtonian and the Boussinesq approximation is valid. The governing equations have been discretized using the finite difference method with the uniform grid. Simulations have been carried out for different values of the Rayleigh number, Hartmann number, Darcy number, magnetic field inclination angle and viscosity variation parameters. Findings It has been revealed that an increase in the viscosity parameters leads to the heat transfer enhancement and convective flow intensification. At the same time, this intensification is more essential for high values of the Rayleigh number. Originality/value The originality of this work is to analyze MHD natural convection in a square porous cavity filled with a water-based magnetic fluid of geothermal viscosity. The results would benefit scientists and engineers to become familiar with the analysis of convective heat and mass transfer in nanofluids, and the way to predict the properties of nanofluid convective flow in advanced technical systems, in industrial sectors including transportation, power generation, chemical sectors and electronics.

Analysis of Entropy Generation of a Magneto-Hydrodynamic Flow Through the Operation of an Unlooped Pulsating Heat Pipe

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Mobadersani Farrokh ◽  
Toolabi Goodarz ◽  
Jafarmadar Samad ◽  
Nasiri Javid ◽  
Habibzadeh Amin
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Pipe ◽  
Entropy Generation ◽  
Uniform Magnetic Field ◽  
Pipe Diameter ◽  
Bejan Number ◽  
Pulsating Heat Pipe ◽  
Viscous Effects ◽  
Evaporator Temperature

The aim of the study is the analysis of a uniform magnetic field effect on fluid flow, heat transfer, and entropy generation through the operation of a pulsating heat pipe (PHP). An open loop PHP with three neighboring vapor plugs and two liquid slugs has been considered. The governing equations such as momentum, energy, and mass equations are solved using an explicit method except for the energy equation of liquid slugs. For each case study, Bejan number has been derived to find the heat transfer share in entropy generation. According to the results, the performance of the oscillating heat pipe decreases by applying uniform magnetic field. Moreover, the obtained results illustrate the effects of the applied magnetic field position on the heat transfer and the entropy generation. The latent and sensible heat transfer into the PHP enhance as a result of increase in the pipe diameter, so that the liquid slugs oscillate with high amplitudes. In addition, the entropy generation value increases with an augmentation in the value of the pipe diameter. The evaluated Bejan numbers indicate that the viscous effects in entropy generation decrease as the pipe diameter increases. Furthermore, the results depict that the heat transfer performance of PHP improves by increasing temperature difference between evaporator and condenser sections. With an increase in the value of the evaporator temperature, the Bejan number will increase, as a result, this phenomenon reveals the inconsiderable role of viscous impacts in high evaporator temperatures. In order to validate the calculations, the calculated results have been compared with the previous studies which show good agreement.

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