Combined Effects of Sequential Velocity and Variable Magnetic Field on the Phase Change Process in a 3D Cylinder Having a Conic-Shaped PCM-Packed Bed System

Effects of sequential velocity and variable magnetic field on the phase change during hybrid nanofluid convection through a 3D cylinder containing a phase-change material packed bed (PCM-PB) system is analyzed with the finite element method. As the heat transfer fluid, 40% ethylene glycol with hybrid TiO2-Al2O3 nanoparticles is considered. Impacts of the sequential velocity parameter (K, between 0.5 and 1.5), geometric factor of the conic-shaped PCM-PB (M, between 0.2 and 0.9), magnetic field strength (Ha number between 0 and 50) and solid volume fraction of hybrid nanoparticles (vol.% between 0.02% and 0.1%) on the phase change dynamics are explored. Effects of both constant and varying magnetic fields on the phase change process were considered. Due to the increased fluid velocity at the walls, the phase change becomes higher with higher values of the sequential velocity parameter (K). There is a 21.6% reduction in phase transition time (tF) between the smallest and highest values of K both in the absence and presence of a constant magnetic field. The value of tF is reduced with higher magnetic field strength and the amount of reduction depends upon the sequential velocity parameter. At K = 1.5, the reduction amount with the highest Ha number is 14.7%, while it is 26% at K = 0.5. When nanoparticle is loaded in the base fluid, the value of tF is further reduced. In the absence of a magnetic field, the amount of phase-transition time reduction is 6.9%, while at Ha = 50, it is 11.7%. The phase change process can be controlled with varying magnetic field parameters as well. As the wave number and amplitude of the varying magnetic field are considered, significant changes in the tF are observed.

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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 ◽

10.3390/math9202566 ◽

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.

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Impacts of using an elastic fin on the phase change process under magnetic field during hybrid nanoliquid convection through a PCM-packed bed system

International Journal of Mechanical Sciences ◽

10.1016/j.ijmecsci.2021.106958 ◽

2021 ◽

pp. 106958

Author(s):

Fatih Selimefendigil ◽

Hakan F. Öztop

Keyword(s):

Magnetic Field ◽

Phase Change ◽

Change Process ◽

Packed Bed ◽

Phase Change Process

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Ultralow-fluence single-shot optical crystalline-to-amorphous phase transition in Ge–Sb–Te nanoparticles

Nanoscale ◽

10.1039/c8nr04350g ◽

2018 ◽

Vol 10 (35) ◽

pp. 16574-16580 ◽

Cited By ~ 3

Author(s):

Barbara Casarin ◽

Antonio Caretta ◽

Bin Chen ◽

Bart J. Kooi ◽

Roberta Ciprian ◽

...

Keyword(s):

Phase Transition ◽

Laser Pulse ◽

Phase Change ◽

Amorphous Phase ◽

Change Process ◽

Single Laser Pulse ◽

Single Shot ◽

Single Laser ◽

Phase Change Process

Ge2Sb2Te5 crystalline nanoparticles amorphize through a single laser pulse with exceptional low fluence, boosting the energetics of a phase-change process.

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Optimization of analytical performance of a graphite furnace atomic absorption spectrometer with Zeeman-effect background correction using variable magnetic field strength

Spectrochimica Acta Part B Atomic Spectroscopy ◽

10.1016/s0584-8547(03)00141-1 ◽

2003 ◽

Vol 58 (9) ◽

pp. 1663-1678 ◽

Cited By ~ 25

Author(s):

H Gleisner

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Atomic Absorption ◽

Magnetic Field Strength ◽

Graphite Furnace ◽

Zeeman Effect ◽

Variable Magnetic Field ◽

Atomic Absorption Spectrometer ◽

Graphite Furnace Atomic Absorption ◽

Absorption Spectrometer

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Phase Change and Magneto-Rheology of a Suspension Composed of Magnetic Rod-Like Particles

Volume 7A: Fluids Engineering Systems and Technologies ◽

10.1115/imece2015-51263 ◽

2015 ◽

Author(s):

Akira Satoh

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Phase Change ◽

Rheological Properties ◽

Magnetic Field Strength ◽

Magnetic Particles ◽

Magnetic Particle ◽

Magneto Rheological ◽

Aggregate Structures ◽

The Magnetic Field

Magnetic particle suspensions have a great potential as an application in engineering fields and therefore a variety of studies on these functional fluid have been conducted in various fields, including the traditional fluid engineering field and the recent bioengineering field such as an application to a drug delivery system. The main application target in the fluid engineering field may be mechanical dampers and actuators. Magneto-rheological properties significantly depend on the formation of aggregates of magnetic particles. In the present study, we focus on a ferromagnetic rod-like particle suspension to discuss the phase change of aggregate structures of magnetic rod-like particles and the magneto-rheological properties that are strongly dependent on the formation of aggregate structures. The characteristics of the phase change are mainly investigated by Monte Carlo simulations for thermodynamic equilibrium and the magneto-rheological properties are done by Brownian dynamics simulations in a simple shear flow situation. From the latter simulations, we discuss mainly the dependence of the magneto-rheological effect on the phase change of aggregate structures. In a weak applied magnetic field, magnetic rod-like particles tend to aggregate to form raft-like clusters if the magnetic particle-particle interaction is much stronger than thermal energy. If the magnetic field strength is increased, these raft-like clusters drastically dissociate into single-moving particles at a certain value of the magnetic field strength, that is, the phase change in aggregate structures arises. The net viscosity and viscosity components exhibit complex dependence on the magnetic field strength, which is mainly due to the raft-like cluster formation of magnetic particles.

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Effects of magnetic field, binary particle loading and rotational conic surface on phase change process in a PCM filled cylinder

Case Studies in Thermal Engineering ◽

10.1016/j.csite.2021.101456 ◽

2021 ◽

pp. 101456

Author(s):

Kaouther Ghachem ◽

Fatih Selimefendigil ◽

Hakan F. Öztop ◽

Mohammed Almeshaal ◽

Muapper Alhadri ◽

...

Keyword(s):

Magnetic Field ◽

Phase Change ◽

Change Process ◽

Particle Loading ◽

Phase Change Process ◽

Conic Surface

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Mode Transitions in Hall-Effect Thrusters Induced by Variable Magnetic Field Strength

Journal of Propulsion and Power ◽

10.2514/1.b35709 ◽

2016 ◽

Vol 32 (4) ◽

pp. 903-917 ◽

Cited By ~ 23

Author(s):

Michael J. Sekerak ◽

Alec D. Gallimore ◽

Daniel L. Brown ◽

Richard R. Hofer ◽

James E. Polk

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Hall Effect ◽

Magnetic Field Strength ◽

Variable Magnetic Field ◽

Hall Effect Thrusters ◽

Mode Transitions

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On the Configuration of the Magnetic Field of β CrB

International Astronomical Union Colloquium ◽

10.1017/s0252921100080933 ◽

1976 ◽

Vol 32 ◽

pp. 613-622

Author(s):

I.A. Aslanov ◽

Yu.S. Rustamov

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Radial Velocity ◽

Magnetic Field Strength ◽

Complex Shape ◽

Rotation Period ◽

Field Variation ◽

Magnetic Field Variation ◽

Secular Variations ◽

The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

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