Browsing by Author "Albalawi H."

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    Thermal and phase change process of nanofluid in a wavy PCM installed triangular elastic walled ventilated enclosure under magnetic field
    (Elsevier Ltd, 2023) Selimefendigil F.; Ghachem K.; Albalawi H.; Alshammari B.M.; Labidi T.; Kolsi L.
    Coupled interactions between magnetic field, wall elasticity and corrugation of the packed bed container on the phase change and thermal process are analyzed during nanofluid convection in a triangular shaped vented cavity. The numerical analysis is performed considering Cauchy number (Ca between 10−7 and 5×10−5), Hartmann number (Ha between 0 and 50), number of waves (N between 1 and 8) and nanoparticle solid volume fraction (SV-F between 0 and 2%). Higher values of Ca and Ha contributes positively to the phase change and thermal process. The reduction of phase transition time (TP) reduces by 23% at the highest Ca while heat transfer improvements of 22.8% are obtained. The optimum value of wave number is found as N = 2. The optimum configuration is found for elastic wall case at the parameters (50, 2, 2%). The heat transfer enhancement factor is found as 13.8 while the TP reduction is 5% as compared to worst case which is found at (Ha, N, SV-F) = (0, 8, 0) with rigid wall. © 2023 The Author(s)
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    Convective Heat Transfer and Entropy Generation for Nano-Jet Impingement Cooling of a Moving Hot Surface under the Effects of Multiple Rotating Cylinders and Magnetic Field
    (MDPI, 2023) Kolsi L.; Selimefendigil F.; Larguech S.; Ghachem K.; Albalawi H.; Alshammari B.M.; Labidi T.
    In this study, confined slot nano-jet impingement cooling of a hot moving surface is investigated under the combined utilization multiple rotating cylinders and magnetic field. Both convective heat transfer and entropy generation analysis are conducted using a finite element method. Parametric variation of the rotational Reynolds number (Rew between −500 and 500), velocity ratio (VR between 0 and 0.25), Hartmann number (Ha between 0 and 20) and the horizontal location of cylinders (Mx between −8 and 8) are considered. Rotation of the cylinders generally resulted in the degradation of cooling performance while increasing the wall velocity, and the horizontal location of the cylinder was found to positively contribute to this. Heat transfer rate reductions of 20% and 12.5% are obtained using rotations at the highest Rew for the case of stationary (VR = 0) and moving wall (VR = 0.25). When magnetic field at the highest strength is imposed in the rotating cylinder case, the cooling performance is increased by about 18.6%, while it is reduced by about 28% for the non-rotating cylinder case. The hot wall movement contributes, by about 14%, to the overall cooling performance enhancement. Away from the inlet location of the rotating cylinders, thermal performance improvement of 12% is obtained. The entropy generation rises with higher hot wall velocity and higher horizontal distances of the rotating cylinders, while it is reduced with a higher magnetic field for non-rotating cylinders. The best configurations in terms of cooling performance provide 8.7% and 34.2% enhancements for non-rotating and rotating cylinders compared with the reference case of (Rew, VR, Ha, Mx) = (0, 0, 0, 0), while entropy generation becomes 1% and 15% higher. © 2023 by the authors.
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    Effects of a conductive T-shaped partition on the phase change dynamics in a channel equipped with multiple encapsulated PCMs under different magnetic fields
    (Elsevier Ltd, 2024) Selimefendigil F.; Ghachem K.; Albalawi H.; Alshammari B.M.; Labidi T.; Kolsi L.
    For enhanced thermal management and energy storage, an understanding of the phase change process and how to control it is crucial in many different engineering applications. In this study, effects of using a T-shaped conductive partition on the phase change process in a multiple phase change material-installed three dimensional cylinder are explored by using finite element method. In the computational domain, a uniform magnetic field with varying strengths is applied. The investigation is conducted for various Reynolds numbers (Re:200–500), Hartmann number of the first and second domains (Ha1: 0–50 and Ha2: 0–50), partitions sizes (Lp: 0.05L–0.5L), and conductivity ratios (KR:0.01–100). The entire transition times (trF) of the left and right phase change materials decrease with increasing Re and Ha. At Ha1=0, the reduction amounts of trF with Re for phase change materials P1 and P2 are 24.40% and 27.45%, respectively. When magnetic field is imposed at Ha1=50, the amounts are 19.4% and 22.7%. The size of the conductive partition affects the size of the vortex established within the phase change material zone. When the partition size is altered, the tr-F variation for P1 and P2 in the absence of magnetic field is 11% and 8.5%, respectively, but in the presence of magnetic field it is 26.5% and 7%. The partition's conductivity has an impact on the dynamics of phase changes as well. The phase completion times of the various phase change materials differ most at KR=0.1, and at that moment, P1's trF is 42% higher than P2's. When modeling the time-dependent variation of liquid fraction for various phase change materials and conductivity ratios, a polynomial type regression model is employed. The findings are useful for the initial design, thermal management and the optimization studies of phase change material embedded systems in a variety of applications, such as heat recovery systems, convective heat transfer applications, and the cooling of electronic equipments. © 2024 The Author(s)
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    Magneto-convection of nanofluid flow over multiple rotating cylinders in a confined space with elastic walls and ventilated ports
    (Elsevier Ltd, 2024) Selimefendigil F.; Ghachem K.; Albalawi H.; AlShammari B.M.; Labidi T.; Kolsi L.
    In this study, convective heat transfer for nanofluid flow over multiple rotating cylinder in a confined space is analyzed under magnetic field while enclosure has one inlet and one outlet port. Three identical circular cylinder are used and the two walls of the cavity are considered to be elastic. The coupled fluid-structure interaction and magneto-convection problem is solved by finite element method. Impacts of rotational Reynolds number (Rew between -100 and 100), Hartmann number (Ha between 0 and 50), cylinder size (R between 0.001H and 0.11H) and Cauchy number (Ca between 10−8 and 10−3) on the flow and thermal performance features are explored. The flow field and recirculation inside the cavity are significantly affected by the activation of rotation and magnetic field. The vortices are suppressed by increasing the strength of magnetic field and thermal performance is improved. Thermal performance of 56.6% is achieved by activation of magnetic field at the highest strength with rotations of the circular cylinders. When rotations are active, heat transfer rate is reduced while up to 40% reduction is obtained without magnetic field. Cylinder size has the highest impact on the overall thermal performance improvement while up to 132% enhancements are achieved. The contribution of elastic walls on the thermal performance is slight while less than 5% improvements in the average heat transfer is obtained. An optimization study leads to 12.7% higher thermal performance improvements as compared to best case of parametric computational fluid dynamics simulation results while the optimum values of (Rew, Ha, R) is obtained as (-80.66, 50, 0.11H). © 2024 The Author(s)
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    Single-channel cooling system design by using perforated porous insert and modeling with POD for double conductive panel
    (Walter de Gruyter GmbH, 2024) Selimefendigil F.; Benabdallah F.; Ghachem K.; Albalawi H.; Alshammari B.M.; Kolsi L.
    In this study, a single cooling channel system is suggested for conductive double panel systems. The cooling channel for the vertical component uses perforated porous insert (PP-I) and porous insert (P-I), while cylinders are used in the PP-I case. The permeability of the porous channel (Da between 1 0-5 and 1 0-1, size of the cylinders (Rc between 0 and 0.25), and location of the PP plate (Yp between 1 and 4.5) are all taken into account when calculating the effectiveness of the cooling system using finite element method. It is found that PP-I can effectively control the vortex size and enhance cooling performance, particularly for vertical plate. Nusselt number is enhanced in the absence of cylinders in the vertical channel by 92% as contrasted to 51% in the presence of cylinders. When cylinders are used for the vertical channel, the temperature drop of 1 3 ° is computed. The flow field noticeably changes when the permeability of the P-I and PP-I is altered. The equivalent temperature increases for P-I and PP-I with setups at Da = 1 0-5 and Da = 1 0-2 are 7.7 ° and 4.4 ° C, respectively. The performance of cooling for the vertical plate is influenced favorably by the higher values of the porous plate's vertical placement. By moving the porous object, it is possible to reduce the temperature by 8 ° C. For panel surface temperature, a proper orthogonal decomposition (POD)-based reconstruction model with 12 POD modes is used. The POD-based model accurately captures the effects of utilizing P-I and PP-I on the panel temperature. © 2024 the author(s), published by De Gruyter.
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    Effects of using magnetic field and double jet impingement for cooling of a hot oscillating object
    (Elsevier Ltd, 2024) Selimefendigil F.; Ghachem K.; Albalawi H.; Alshammari B.M.; Labidi T.; Kolsi L.
    Efficient cooling system design with impinging jets becomes an important topic due to its higher cooling performance applicable to engineering systems such as in electronic cooling, photovoltaic panels and material processing. In the present study, cooling of an oscillating hot object is considered by using a double slot jet impingement system in the presence of a uniform inclined magnetic field. The oscillation of body and magnetic field can be present in the system or they can be considered as methods for flow and convective heat transfer control for the slot-jet impingement system. Analysis is done for a range of values for the jet Reynolds number (Re ranging from 100 to 500), Hartmann number (Ha, ranging from 0 to 10), inclination of magnetic field (γ, ranging from 0 to 90), and oscillation amplitude (Amp, between −3 and 3) by using finite element method with Arbitrary Lagrangian–Eulerian technique. It is observed that due to the hot object's oscillating nature, cooling is either increased or worsened for different time steps based. When Re is raised from the lowest to highest value, average Nusselt number (Nu) increases by a factor of 2.4. In the cooling system with impinging jets, strength of magnetic field and its inclination may be employed to regulate the vortex size and distribution. In comparison to the absence of magnetic field, the average Nu falls by around 73% to 75.5% at the greatest magnetic field strength. When oscillation is enabled, cooling performance is increased adopting the time step. By comparing the oscillating object with stationary one, cooling performance improvements of 28% and 8.3% are obtained at (Re, Ha)=(500, 0), and (500, 10) parametric combinations. © 2024 The Author(s)
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    Effects of using sinusoidal porous object (SPO) and perforated porous object (PPO) on the cooling performance of nano-enhanced multiple slot jet impingement for a conductive panel system
    (KeAi Communications Co., 2024) Selimefendigil F.; Benabdallah F.; Ghachem K.; Albalawi H.; Alshammari B.M.; Kolsi L.
    Cooling system design for thermal management of electronic equipment, batteries and photovoltaic (PV) modules is important for increasing the efficiency, safety operation, and long life span the products. In the present study, two different cooling systems are proposed with nano-enhanced multiple impinging jets for a conductive panel. The present cooling systems can be used in electronic cooling and PV modules. Perforated porous object (PPO) and sinusoidal porous object (SPO) are used in the jet cooling system. 2D numerical analysis using finite volume method is conducted considering different values of permeability of the objects (Darcy number (Da) between 10−6 and 10−1). When PPO is used in the cooling system, number of cylinders (between 1 and 6), and size of the cylinders (between 0.015 and 0.075) are considered. In the case of using SPO, amplitude (between 0.1 and 2) and wave number (between 1 and 12) are varied. Alumina-water nanofluid with cylindrical shaped nanoparticles is used as the heat transfer fluid. When permeability is changed for PPO, the average temperature increases by roughly 3.89 °C for a single cylinder and drops by roughly 0.57 °C for a six-cylinder cases. Increasing the size of the cylinder in the PPO case at highest permeability results in temperature drop of 5.3 °C. When changing the number of cylinders, cooling rate varies by about 3.6%. Wave number of SPO is more influential on the cooling performance enhancement as compared to amplitude and permeability of the SPO. The average surface temperature drops by 12.4 °C when the wave number is increased to 12. As compared to reference case of jet impingement cooling without porous object, using PPO and SPO along with the nanofluid result in temperature drop of 12.3 °C and 14.4 °C. © 2024 The Authors
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    Nanofluid cooling of a hot rotating circular cylinder employing cross-flow channel cooling on the upper part and multi-jet impingement cooling on the lower part
    (American Institute of Physics, 2024) Selimefendigil F.; Larguech S.; Ghachem K.; Albalawi H.; Alshammari B.M.; Labidi T.; Kolsi L.
    This study explores the convective cooling features of a hot rotating cylinder by using the combined utilization of cross-flow on the upper part and multi-jet impingement on the bottom part. The analysis is performed for a range of jet Reynolds number (Re) values (between 100 and 500), cross-flow Re values (between 100 and 1000), rotational Re values (between −1000 and 1000), cylinder size (between 0.25wj and 3wj in radius), and center placement in the y direction (between −1.5wj and 1.5wj). When the cylinder is not rotating, the average Nu increment becomes 102% at the highest jet Re, while it becomes 140.82% at the highest cross-flow Re. When rations become active, the impacts of cross-flow and jet impingement cooling become slight. As compared to a motionless cylinder, at the highest speed of the rotating cylinder, the average Nu rises by about 357% to 391%. For clockwise rotation of the cylinder, a lager cylinder results an increase in the average Nu by about 86.3%. At the lowest and highest cross-flow impinging jet Re value combinations, cooling performance improvement becomes a factor of 8.1 and 2, respectively. When the size of the cylinder changes, entropy generation becomes significant, while the vertical location of the cylinder has a slight impact on entropy generation. © 2024 Author(s).