Browsing by Author "Ladhar L."

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    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
    (MDPI, 2021) Kolsi L.; Selimefendigil F.; Omri M.; Ladhar L.
    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. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
  • No Thumbnail Available
    Item
    Analysis of MHD nanofluid forced convection and phase change process in a PCM mounted corrugated and partly elastic partitioned channel system with area expansion
    (Elsevier B.V., 2024) Omri M.; Selimefendigil F.; Besbes H.; Ladhar L.; Alshammari B.M.; Kolsi L.
    In this study, effects of using wall corrugation and nano-enhanced magnetic field in a channel with area expansion and elastic interface on the phase change and thermal process are examined by using finite element method with ALE (Arbitrary Lagrangian-Eulerian). A range of values for the relevant parameters are included in the simulations: the flow Reynolds number (Re) between 100 and 1000; the elasticity of the flexible partition (E between 105 and 109); the Hartmann number (Ha) between 0 and 60; the amplitude of the wavy wall (A between 0.01 and 0.35); and the wave number of corrugation (N between 2 and 20). Complete phase transition (tF) with Re shows non-monotonic behavior while variations of tF up to 57 % and 50 % are obtained for the upper and lower PCM under wavy wall with varying Re. For upper PCM, the variation of tF with elastic modulus becomes 21 %-25 %. When E is changed, the average Nu increment with a corrugated wall is 11 %. When the magnetic field is applied with maximal strength, thermal performance is enhanced and the phase transition process is accelerated. For the upper and lower PCM zones, reduction of tF with Ha yields 44 % and 33 %, respectively. For the upper and lower PCM zones, the full transition time decreases with higher corrugation amplitudes by 14.7 % and 12.5 %, respectively. Average Nu increments of 10 % and 7.5 % are found by raising the corrugation amplitude and wave number to their maximum values. A significant reduction of tF, around 54 %, is obtained with the introduction of wavy walls with magnetic field and nanofluid when compared to the reference case (flat channel using base fluid and without magnetic field effects). Although the upper wall's corrugation further enhances thermal performance, magnetic field has a bigger impact on thermal performance than wavy shape. © 2024 The Authors