Browsing by Subject "Outlet port"

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    MHD mixed convection of nanofluid in a three-dimensional vented cavity with surface corrugation and inner rotating cylinder
    (Emerald Publishing, 2020) Selimefendigil F.; Chamkha A.J.
    Purpose: This study aims to numerically examine mixed convection of CuO-water nanofluid in a three-dimensional (3D) vented cavity with inlet and outlet ports under the influence of an inner rotating circular cylinder, homogeneous magnetic field and surface corrugation effects. In practical applications, it is possible to encounter some of the considered configurations in a vented cavity such as magnetic field, rotating cylinder and it is also possible to specially add some of the active and passive control means to control the convection inside the cavity such as adding nanoparticles, corrugating the surfaces. The complicated physics with nanofluid under the effects of magnetic field and inclusion of complex 3D geometry make it possible to use the results of this numerical investigation for the design, control and optimization of many thermal engineering systems as mentioned above. Design/methodology/approach: The bottom surface is corrugated with a rectangular wave shape, and the rotating cylinder surface and cavity bottom surface were kept at constant hot temperatures while the cold fluid enters the inlet port with uniform velocity. The complicated interaction between the forced convection and buoyancy-driven convection coupled with corrugated and rotating surfaces in 3D configuration with magnetic field, which covers a wide range of thermal engineering applications, are numerically simulated with finite element method. Effects of various pertinent parameters such as Richardson number (between 0.01 and 100), Hartmann number (between 0 and 1,000), angular rotational speed of the cylinder (between −30 and 30), solid nanoparticle volume fraction (between 0 and 0.04), corrugation height (between 0 and 0.18H) and number (between 1 and 20) on the convective heat transfer performance are numerically analyzed. Findings: It was observed that the magnetic field suppresses the recirculation zone obtained in the lower part of the inlet port and enhances the average heat transfer rate, which is 10.77 per cent for water and 6.86 per cent for nanofluid at the highest strength. Due to the thermal and electrical conductivity enhancement of nanofluid, there is 5 per cent discrepancy in the Nusselt number augmentation with the nanoadditive inclusion in the absence and presence of magnetic field. The average heat transfer rate of the corrugated surface enhances by about 9.5 per cent for counter-clockwise rotation at angular rotational speed of 30 rad/s as compared to motionless cylinder case. Convective heat transfer characteristics are influenced by introducing the corrugation waves. As compared to number of waves, the height of the corrugation has a slight effect on the heat transfer variation. When the number of rectangular waves increases from N = 1 to N = 20, approximately 59 per cent of the average heat transfer reduction is achieved. Originality/value: In this study, mixed convection of CuO-water nanofluid in a 3D vented cavity with inlet and outlet ports is numerically examined under the influence of an inner rotating circular cylinder, homogeneous magnetic field and surface corrugation effects. To the best of authors knowledge such a study has never been performed. In practical applications, it is possible to encounter some of the considered configurations in a vented cavity such as magnetic field, rotating cylinder and it is also possible to specially add some of the active and passive control means to control the convection inside the cavity such as adding nanoparticles, corrugating the surfaces. The complicated physics with nanofluid under the effects of magnetic field and inclusion of complex 3D geometry make it possible to use the results of this numerical investigation for the design, control and optimization of many thermal engineering systems as mentioned above. © 2019, Emerald Publishing Limited.
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    Impacts of using a piezo-mounted elastic fin energy harvester on the power production and heat transfer control in a ventilated cavity during turbulent forced convection
    (Elsevier Ltd, 2024) Selimefendigil F.; Altammar H.; Oztop H.F.
    Piezo-electric energy harvesters (PE-EH) are used in a variety of engineering applications due to their simplicity, ease of installation, compact structure, higher power density, and lower cost. In this study, a novel elastic PE-EH fin assembly within a ventilated cavity is proposed for thermal management and power production during forced convection in turbulent flow regimes by using finite element method with ALE. Impacts of Reynolds number (Re between 10,000 and 50,000), opening ratio (OR between 0.5 and 2), fin vertical placement (yf between −0.3H and 0.3H), and inlet port horizontal position (xi between 0 and 0.6H) on the characteristics of generated power and convective heat transfer are numerically assessed. Higher deflection of the elastic fin assembly and vortex size reduction at the fin tip are the outcomes of higher Re and OR values. The average Nu rises by about 135% for Re values between Re = 10,000 and Re = 30,000 but reduces by 55% between Re = 30,000 and Re = 50,000. Cooling performance is improved by 165% when OR variation is taken into account, going from the lowest value of OR to OR = 1.5. For generated power, the enhancement factors are 290 and 81 when values of Re and OR are raised from their lowest to highest levels. For cooling performance and generated power, the corresponding improvement factors are 6.94 and 2.5, respectively, from the lowest to the maximum value of the vertical position. Inlet and outlet port locations closer to the middle of the top and bottom wall provides the highest power generation from the PE-EH. There are 121% and 41% variations of generated power when inlet and outlet port locations are varied. An artificial neural network is used to assess the power generated by the PE-EH device using a three-input, one-output system. © 2024 Elsevier Ltd