Browsing by Author "Sheikholeslami, M"

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    Energy storage analysis for discharging of nanoparticle enhanced phase change material within a triplex-tube thermal storage
    Zhang, XJ; Sheikholeslami, M; Yan, WM; Shafee, A; Selimefendigil, F; Babazadeh, H
    In current transient modeling, discharging of PCM based on FEM has been scrutinized. Due to importance of phenomenon near the solid front, time linked mesh has been employed and to reduce the thermal irreversibility, copper oxide nanomaterial was dispersed into H2O. Outputs indicate that using wavy wall and dispersing Platelet copper oxide are capable for expedition of discharging. Obtaining the completed solidification in minimum time is main criteria for designing a storage unit. Changing shape of nanoparticle from spherical to Platelet can reduce the solidification duration about 5.96%. Utilizing greater amplitude of sinusoidal wall can reduce the discharging time by about 7.58% which is related to stronger conduction mechanism. Inclusion of nanoparticles, not only improve the phase change rate but also decline the irreversibility due to lower temperature of domain. Needed time declines about 22.7% with disperse of platelet CuO. As shape of powder changes from platelet to sphere, required time alters from 337.41 s to 358.8 s. The solidification rate for A = 0.3 is 1.06 times greater than that of A = 0.1.
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    Phase change process of nanoparticle enhanced PCM in a heat storage including unsteady conduction
    Shafee, A; Sheikholeslami, M; Wang, P; Selimefendigil, F; Babazadeh, H
    Thermal energy release process during solidification of water has been simulated in current investigation. Time-linked equation was solved via Galerkin approach and automatic time step has been considered. To augment thermal characteristics, NEPCM has been fabricated by embedding copper oxide in to water. Low deviation with experimental data confirms the accuracy of current code. With reduce of concentration of nanomaterial, process prolonged and higher temperature of domain has been reported. Selecting greater shape factor yields to stronger conduction mode which can result unit with lower solidification time. There was an approximate 1.34% reduction in discharging time with augment of shape factor and such percentage reaches to 4.6% for nanomaterial with 0.04 volume fraction. There is reducing tendency in time of solidification with augment of concentration of nanomaterial and outputs showed that 14.39% reduction for platelet CuO nano powders. Energy released reduces as time augments due to reduction in mass of liquid phase. (C) 2020 Elsevier B.V. All rights reserved.
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    Numerical modeling of turbulent behavior of nanomaterial exergy loss and flow through a circular channel
    Shafee, A; Sheikholeslami, M; Jafaryar, M; Selimefendigil, F; Bhatti, MM; Babazadeh, H
    To understand the impacts of adding twisted tape inside the tube with hybrid nanomaterial, the present paper has been examined with considering FVM. New testing fluid instead of water leads to lower exergy loss. Modeling outputs were carried out for different pitch ratio and Reynolds number. Decrement trend for secondary flow was reported when pitch ratio increases, and for this reason, convective flow reduces with rise ofPwhich results in greater exergy drop. Turbulence intensity improves with augment of Re which provides stronger interaction of nanomaterial and tube wall. So, thinner boundary layer appears with rise of Re and exergy loss deteriorates.
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    Hydrothermal analysis of nanoparticles transportation through a porous compound cavity utilizing two temperature model and radiation heat transfer under the effects of magnetic field
    Li, ZX; Selimefendigil, F; Sheikholeslami, M; Shafee, A; Alghamdi, M
    In current text, we developed CVFEM code for nanomaterial hydrothermal management through a permeable compound cavity including two temperature model. Radiation and Lorentz source terms were added in formulations. Impacts of radiation parameter, Rayleigh, Hartmann number, interface heat transfer parameter and nanoparticles' shape on nanofluid behavior were demonstrated. Contours indicate that convective mode becomes stronger with augment of buoyancy term. By increasing Nhs, conduction becomes more effective and Nusselt number reduces. As radiation term enhances, Nusselt number augments.
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    Impact of local elasticity and inner rotating circular cylinder on the magneto-hydrodynamics forced convection and entropy generation of nanofluid in a U-shaped vented cavity
    Selimefendigil, F; Öztop, HF; Sheikholeslami, M
    This study analyzes the effects of a partial elastic wall and rotating circular cylinder on the convective heat transfer of carbon nanotube (CNT)-water nanofluid filled U-shaped cavity with entropy generation by considering inclined magnetic field effects. Numerical simulation is performed by using ALE with finite element method (FEM). Impacts of various important parameters such as Re number, Ha number, magnetic field orientation, elastic wall size and modulus, angular velocity, and horizontal position of the rotating cylinder on the forced convection are analyzed. When the values of Re number, strength of magnetic field (up to Ha number of 50), and orientation angle are increased, the average Nu value rises while the impact is opposite for higher elastic wall size and horizontal position of the cylinder above 0.4H. When the rotational cylinder effects are considered, enhancement up to 60%is obtained at the highest speed as compared to motionless cylinder case. The average Nu variation is in the range of 9%-10.45%at the highest value when varying the size and modulus of the elastic wall. Flexible wall effects on the average Nu number variation becomes more pronounced when the angular rotational velocity is highest at the clockwise rotation and for the highest Re number. The average Nu number enhancements are 13%-14%at the highest Ha number. The entropy generation rates with varying Ha number, rotational velocity, and location of the cylinder are different for the left and right parts of the domains while impacts of elastic wall properties on the entropy generation rate are slight.