Browsing by Author "Alshammari B.M."
Now showing 1 - 16 of 16
Results Per Page
Sort Options
Item Coupled Effects of Using Magnetic Field, Rotation and Wavy Porous Layer on the Forced Convection of Hybrid Nanoliquid Flow over 3D-Backward Facing Step(MDPI, 2022) Ghachem K.; Selimefendigil F.; Alshammari B.M.; Maatki C.; Kolsi L.In the present study, the effects of using a corrugated porous layer on the forced convection of a hybrid nanofluid flow over a 3D backward facing step are analyzed under the coupled effects of magnetic field and surface rotation. The thermal analysis is conducted for different values of the Reynolds number (Re between 100 and 500), the rotational Reynolds number (Rew between 0 and 2000), the Hartmann number (Ha between 0 and 15), the permeability of the porous layer (the Darcy number, Da between (Formula presented.) and (Formula presented.)) and the amplitude (ax between 0.01 ap and 0.7 ap) and wave number (N between 1 and 16) of the porous layer corrugation. When rotations are activated, the average Nusselt number (Nu) and pressure coefficient values rise, while the increment of the latter is less. The increment in the average Nu is higher for the case with a higher permeability of the layer. When the corrugation amplitude and wave number are increased, favorable impacts of the average Nu are observed, but at the same time pressure coefficients are increased. Successful thermal performance estimations are made by using a neural-based modeling approach with a four input-two output system. © 2022 by the authors.Item Application and CFD-Based Optimization of a Novel Porous Object for Confined Slot Jet Impingement Cooling Systems under a Magnetic Field(MDPI, 2022) Aich W.; Selimefendigil F.; Ayadi B.; Ben Said L.; Alshammari B.M.; Kolsi L.; Betrouni S.A.; Gasmi H.A novel porous object for the control of the convective heat transfer of confined slot nanojet impingement is offered under magnetic field effects, while optimization-assisted computational fluid dynamics is used to find the best working conditions to achieve the best performance of the system. The flow, thermal patterns, and heat transfer characteristics were influenced by the variation in rotational Reynolds number (Rew), Hartmann number (Ha), permeability of the porous object (Da) and its location (Mx). There was a 14.5% difference in the average Nusselt number (Nu) at the highest Rew when motionless object configuration at Ha = 5 was compared, while it was less than 2% at Ha = 25. At Rew = −600, the average Nu variation was 22% when cases with the lowest and highest magnetic field strength were compared. The porous object provides an excellent tool for convective heat transfer control, while the best performance was achieved by using optimization-assisted computational fluid dynamics. The optimal sets of (Rew, Da, Mx, AR) for porous object were (−315.97, 0.0188, −1.456, 0.235), (−181.167, 0.0167, −1.441, 0.2), and (−483.13, 0.0210, −0.348, 0.2) at Ha = 5, 10, and 25, respectively. At the optimal operating point, the local Nu enhancements were 19.46%, 44.86%, and −0.54% at Ha = 5, 10, and 15, respectively, when the no-object case was compared, while the average values were 7.87%, 8.09% and 5.04%. © 2022 by the authors.Item 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)Item Multiple slot nano-jet impingement cooling of a sinusoidal hot surface by using active rotating cylinders under magnetic field(Elsevier Ltd, 2023) Selimefendigil F.; Ghachem K.; Alwadai N.; Alshammari B.M.; Kolsi L.In this study, cooling performance of a multi-slot jet impingement system for a wavy surface are explored under the triple combined effects of using magnetic field (MG-F), double active rotating cylinders and nanofluid. Double rotating cylinders which provide additional cooling are used while Galerkin weighed residual finite element method is used for the solution of the governing equations. Effects of Rew (rotational Reynolds number, between −1000 and 1000), Ha (MG-F strength between 0 and 30), MG-F inclination (between 0 and 90) and sub-cooling temperature of the active cylinders (dT between 0 and 10) on the cooling performance are assessed. Rotations of the double cylinders generally provide higher Nusselt number (Nu) while 41% and 18.9% increment in the Nu is obtained when using pure fluid and nanofluid. The average Nu behavior is different when using MG-F depending upon the rotations are active or not. Average Nu is sharply reduced by about 25.1% without rotations but it rises by about 89% at Ha = 10 by using rotations. The impacts of sub-cooling is very effective when rotations are active while up to 37.9% rise of Nu is obtained at Rew = −1000. When no cylinders are used, using MG-F reduced the average Nu by about 15.4%. The best cooling performance case in the absence of MG-F with cylinders is obtained at Rew = −1000 and dT = 10. © 2023 The Author(s)Item 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.Item Conjugate Heat Transfer Analysis for Cooling of a Conductive Panel by Combined Utilization of Nanoimpinging Jets and Double Rotating Cylinders(MDPI, 2023) Kolsi L.; Selimefendigil F.; Gasmi H.; Alshammari B.M.In this work, double rotating active cylinders and slot nanojet impingement are considered for the cooling system of a conductive panel. Colder surface temperatures of the cylinders are used, while different rotational speeds are assigned for each of the cylinders. The impacts of cylinder rotational speeds, size and distance between them on the cooling performance are evaluated. The rotational effects and size of the cylinders are found to be very effective on the overall thermal performance. At the highest rotational speeds of the cylinders, the average Nusselt number (Nu) rises by about 30.8%, while the panel temperature drops by about 5.84 (Formula presented.) C. When increasing the cylinder sizes, temperature drops become 7 (Formula presented.) C, while they are only 1.75 (Formula presented.) C when varying the distance between the cylinders. Subcooling and nanofluid utilization contributes positively to the cooling performance, while 1.25 (Formula presented.) C and 10 (Formula presented.) C temperature drops are found by varying the subcooled temperature and solid volume fraction. An artificial neural network is used for the estimation of maximum and average panel temperatures when double cylinder parameters are used as the input. © 2023 by the authors.Item MHD hybrid nanofluid convection and phase change process in an L-shaped vented cavity equipped with an inner rotating cylinder and PCM-packed bed system(Elsevier B.V., 2023) Ouri H.; Selimefendigil F.; Bouterra M.; Omri M.; Alshammari B.M.; Kolsi L.In this study, convective heat transfer and phase change process are analyzed for an L-shaped vented cavity equipped with an inner rotating cylinder and phase change material-packed bed (PCM-PB) system under magnetic field during hybrid nanofluid convection. The numerical work is performed for different values of Reynolds number (Re between 200–1000), rotational Reynolds number (Rew between −1000–1000), size of the cylinder (R between 0.05H-0.15H) and Hartmann number (Ha between 0–40) while hybrid Ag/MgO nanoparticle loading amount in water is 2%. It is observed that the vortex size and their distributions in the cavity and within the PCM-PB system can be controlled by varying rotating cylinder size and rotational speed along with the magnetic field. With higher cylinder size, phase change becomes fast while complete phase transition time (tP) is reduced by about 22% and average Nusselt number (Nu) rises by about 86% at Rew = −1000. Rotational direction of the cylinder is effective for phase transition dynamics while at Rew = −1000, tP rises up to 27% when compared to non-rotating cylinder case. Magnetic field strength is a good parameter for vortex suppression. At the highest strength, phase change becomes fast and average Nu rises up to 26.5% at Rew = −1000. ANFIS based modeling approach is used for impacts of rotating cylinder on the phase change dynamics in the L-shaped vented cavity. © 2022 THE AUTHORSItem CFD Study of MHD and Elastic Wall Effects on the Nanofluid Convection Inside a Ventilated Cavity Including Perforated Porous Object(MDPI, 2023) Kolsi L.; Selimefendigil F.; Omri M.; Rmili H.; Ayadi B.; Maatki C.; Alshammari B.M.Cost-effective, lightweight design alternatives for the thermal management of heat transfer equipment are required. In this study, porous plate and perforated-porous plates are used for nanoliquid convection control in a flexible-walled vented cavity system under uniform magnetic field effects. The finite element technique is employed with the arbitrary Lagrangian–Eulerian (ALE) method. The numerical study is performed for different values of Reynolds number ((Formula presented.)), Hartmann number ((Formula presented.)), Cauchy number ((Formula presented.)) and Darcy number ((Formula presented.)). At Re = 600, the average Nusselt number (Nu) is 6.3% higher by using a perforated porous plate in a cavity when compared to a cavity without a plate, and it is 11.2% lower at Re = 1000. At the highest magnetic field strength, increment amounts of Nu are in the range of 25.4–29.6% by considering the usage of plates. An elastic inclined wall provides higher Nu, while thermal performance improvements in the range of 3.6–6% are achieved when varying the elastic modulus of the wall. When using a perforated porous plate and increasing its permeability, 22.8% increments of average Nu are obtained. A vented cavity without a plate and elastic wall provides the highest thermal performance in the absence of a magnetic field, while using a porous plate with an elastic wall results in higher Nu when a magnetic field is used. © 2023 by the authors.Item Numerical Study of Thermo-Electric Conversion for TEG Mounted Wavy Walled Triangular Vented Cavity Considering Nanofluid with Different-Shaped Nanoparticles(MDPI, 2023) Selimefendigil F.; Omri M.; Aich W.; Besbes H.; Ben Khedher N.; Alshammari B.M.; Kolsi L.The effects of the combined utilization of wavy wall and different nanoparticle shapes in heat transfer fluid for a thermoelectric generator (TEG) mounted vented cavity are numerically analyzed. A triangular wave form of the cavity is used, while spherical and cylindrical-shaped alumina nanoparticles are used in water up to a loading amount of 0.03 as solid volume fraction. The impacts of wave amplitude on flow and output power features are significant compared to those of the wave number. The increment in the generated power is in the range of 74.48–92.4% when the wave amplitude is varied. The nanoparticle shape and loading amount are effective in the rise of the TEG power, while by using cylindrical-shaped nanoparticles, higher powers are produced as compared to spherical ones. The rise in the TEG power by the highest loading amount is achieved as 50.7% with cylindrical-shaped particles, while it is only 4% with spherical-shaped ones. Up to a 194% rise of TEG power is attained by using the triangular wavy form of the wall and including cylindrical-shaped nanoparticles as compared to a flat-walled cavity using only pure fluid. © 2023 by the authors.Item Hybrid Nano-Jet Impingement Cooling of Double Rotating Cylinders Immersed in Porous Medium(MDPI, 2023) Selimefendigil F.; Hamzaoui M.; Aydi A.; Alshammari B.M.; Kolsi L.A cooling system with impinging jets is used extensively in diverse engineering applications, such as solar panels, electronic equipments, battery thermal management, textiles and drying applications. Over the years many methods have been offered to increase the effectiveness of the cooling system design by different techniques. In one of the available methods, nano-jets are used to achieve a higher local and average heat transfer coefficient. In this study, convective cooling of double rotating cylinders embedded in a porous medium is analyzed by using hybrid nano-jets. A finite element formulation of the thermo-fluid system is considered, while impacts of Reynolds number, rotational speed of the double cylinders, permeability of the porous medium and distance between the cylinders on the cooling performance are numerically assessed. Hybrid and pure fluid performances in the jet cooling system are compared. It is observed that the cooling performance improves when the rotating speed of the cylinder, permeability of the medium and jet Reynolds number are increased. The heat transfer behavior when varying the distance between the cylinders is different for the first and second cylinder. Higher thermal performances are achieved when hybrid nanofluid with higher nanoparticle loading is used. An optimization algorithm is used for finding the optimum distance and rotational speeds of the cylinders for obtaining an improved cooling performance, while results show higher effectiveness as compared to a parametric study. The outcomes of the present work are useful for the thermal design and optimization of the cooling system design for configurations encountered in electronic cooling, energy extraction and waste heat recovery. © 2022 by the authors.Item 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)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 AuthorsItem 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.Item 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)Item 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 AuthorsItem 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).