Browsing by Author "Algarni S."

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    Thermal and Phase Change Process in a Locally Curved Open Channel Equipped with PCM-PB and Heater during Nanofluid Convection under Magnetic Field
    (MDPI, 2022) Aich W.; Selimefendigil F.; Alqahtani T.; Algarni S.; Alshehery S.; Kolsi L.
    Thermal performance and phase-change dynamics in a channel having a cavity equipped with a heater and phase-change material (PCM)-packed bed (PB) region are analyzed during nanoliquid convection under an inclined magnetic field. Curvature of the upper wall above the PCM zone is also considered by using the finite element method. Impacts of curvature of the upper wall (between 0.01H and 0.6H, H-channel height), strength of magnetic field (MGF) (Hartmann number between 0 and 40), height (between 0.1H and 0.4H) and number (between 5 and 17) of heaters on the thermal performance and phase-change dynamics are studied. In the interior and wall near regions of the PCM-PB, the curvature effects become opposite, while phase completion time (tF) rises by about 42% at the highest radius of the curvature. Imposing MGF and increasing its strength has positive impacts on the phase change and thermal performance. There is a reduction in tF by about (Formula presented.) and (Formula presented.) when MGF is imposed at Ha = 40 for pure fluids and nanofluids. When thermal performance for all different cases is compared, using MGF+nanofluid+PCM provides the most favorable case. When the reference case (only pure fluid without MGF and PCM) is used, including nanoparticles results in an improvement of 33.7%m while it is further increased to 71.1% when PCM-PB is also installed. The most favorable case by using MGF, nanofluid and PCM-PB results in thermal performance improvement of about 373.9% as compared to the reference configuration. © 2022 by the authors.
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    Enhancing the performance of a greenhouse drying system by using triple-flow solar air collector with nano-enhanced absorber coating
    (Elsevier Ltd, 2022) Selimefendigil F.; Sirin C.; Ghachem K.; Kolsi L.; Alqahtani T.; Algarni S.
    In this research, the impacts of utilizing nano-embedded absorber coating in an auxiliary heater of a greenhouse drying system on the thermal and drying performances have been surveyed empirically. In this context, triple-flow solar air collectors with and without CuO nano-enhanced absorber coating have been designed and manufactured. Designed collectors then integrated to even-span greenhouse dryers to be used as an auxiliary heating device. In the experiments, greenhouse dryers have been tested with and without auxiliary heaters at constant flow rate which is 0.014 kg s-1. According to the experimental findings, utilizing triple-flow solar air heating device with and without nano-embedded paint decreased the drying time as 35.71% and 26.66%, respectively. Thermal and exergetic efficiencies for newly developed collectors were found between the range of 70.39-75.11% and 9.05-10.18%, respectively. In addition, specific energy consumption values were decreased by using collectors with and without nano-enhanced modification from 2.51 to 2.11 and from 2.61 to 2.18 kWh/kg, respectively. Attained outcomes of this study showed the successful utilization of nano-enhanced absorber coating in the auxiliary heating system of the greenhouse dryer. © 2022 The Authors.
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    Pulsating nanofluid flow in a wavy bifurcating channel under partially active uniform magnetic field effects
    (Elsevier Ltd, 2022) Kolsi L.; Selimefendigil F.; Ghachem K.; Alqahtani T.; Algarni S.
    Separated flow and thermal performance characteristics by combined utilization of surface corrugation, partially active magnetic field, nanoparticle loading in the base fluid and flow pulsations are analyzed numerically in a bifurcating channel by using finite element method. Size and number of vortices are affected by the variation corrugation height and wave numbers while the vortices are damped by using partially active magnetic field in different domains. When various methods are compared, by using corrugations highest heat transfer improvement is achieved followed by the flow pulsations and magnetic field. By utilization of nanofluids, thermal performance is further improved. When corrugation height is considered, enhancement up to 248.3% is obtained for wave number of 8 while variation in the average Nusselt number (Nu) becomes only 22.9% with varying wave number. The enhancement amount with pulsating flow amplitude depends upon the nanoparticle loading amount in the base fluid. At solid volume fraction of 0.02%, the average Nu increases by about 79.8% with pulsating flow at the highest amplitude as compared to steady flow case. Dynamic models with system identification are constructed for predictions of time dependent Nu variations for different pulsating amplitudes in the absence and presence of magnetic field for the bifurcating channel. The potential improvement of convective heat transfer in bifurcation channels is explored by combining different novel enhancement methods together. The results of the present analysis will be beneficial for performance improvement and optimization studies of bifurcating channel applications appeared in microelectromechanical systems, fuel cells and thermal management of diverse thermal systems. © 2022 Elsevier Ltd
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    Multiple Impinging Jet Cooling of a Wavy Surface by Using Double Porous Fins under Non-Uniform Magnetic Field
    (MDPI, 2022) Kolsi L.; Selimefendigil F.; Ghachem K.; Alqahtani T.; Algarni S.
    Coupled effects of double porous fins and inhomogeneous magnetic field on the cooling performance of multiple nanojet impingement for a corrugated surface were numerically analyzed. Different values of magnetic field parameters (strength, inclination, and amplitude of spatially varying part) and double porous fin parameters (inclination and permeability) were used, while finite element method is used as the solution method. When parametric computational fluid dynamics (CFD) simulations were performed, there were 162.5% and 34% Nusselt number (Nu) enhancement with magnetic field for flat and wavy surfaces, respectively. The variations of average Nu became 36% and 24% when varying the inclination and amplitude of inhomogeneous magnetic for a flat surface, while the amounts were 43.7% and 32% for a corrugated one. The vortex distribution in between the jets and cooling performance was affected by the variation of double porous fin permeability and inclination. An optimization method was used for the highest cooling performance, while the optimum set of parameters was obtained at (Ha, Amp, Da, Ω) = (0.224, 0.5835, 7.59 × 10−4, 0.1617). By using the double porous fins and inhomogeneous magnetic field, excellent control of the cooling performance of multiple impinging jet was obtained. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.